Sample records for radiation dose estimates

Tables of radiationdoseestimates based on the Cristy-Eckerman adult male phantom are provided for a number of radiopharmaceuticals commonly used in nuclear medicine. Radiationdoseestimates are listed for all major source organs, and several other organs of interest. The doseestimates were calculated using the MIRD Technique as implemented in the MIRDOSE3 computer code, developed by the Oak Ridge Institute for Science and Education, Radiation Internal Dose Information Center. In this code, residence times for source organs are used with decay data from the MIRD Radionuclide Data and Decay Schemes to produce estimates of radiationdose to organs of standardized phantoms representing individuals of different ages. The adult male phantom of the Cristy-Eckerman phantom series is different from the MIRD 5, or Reference Man phantom in several aspects, the most important of which is the difference in the masses and absorbed fractions for the active (red) marrow. The absorbed fractions for flow energy photons striking the marrow are also different. Other minor differences exist, but are not likely to significantly affect doseestimates calculated with the two phantoms. Assumptions which support each of the doseestimates appears at the bottom of the table of estimates for a given radiopharmaceutical. In most cases, the model kinetics or organ residence times are explicitly given. The results presented here can easily be extended to include other radiopharmaceuticals or phantoms.

In evaluating the risk of exposure to health hazards, characterizing the dose-response relationship and estimating acceptable exposure levels are the primary goals. In analyses of health risks associated with exposure to ionizing radiation, while there is a clear agreement that moderate to high radiationdoses cause harmful effects in humans, little has been known about the possible biological effects at low doses, for example, below 0.1 Gy, which is the dose range relevant to most radiation exposures of concern today. A conventional approach to radiationdose-response estimation based on simple parametric forms, such as the linear nonthreshold model, can be misleading in evaluating the risk and, in particular, its uncertainty at low doses. As an alternative approach, we consider a Bayesian semiparametric model that has a connected piece-wise-linear dose-response function with prior distributions having an autoregressive structure among the random slope coefficients defined over closely spaced dose categories. With a simulation study and application to analysis of cancer incidence data among Japanese atomic bomb survivors, we show that this approach can produce smooth and flexible dose-response estimation while reasonably handling the risk uncertainty at low doses and elsewhere. With relatively few assumptions and modeling options to be made by the analyst, the method can be particularly useful in assessing risks associated with low-doseradiation exposures. PMID:26581473

Tumor imaging agents suitable for use with positron emission tomographs are constantly sought. We have performed studies with animal-tumor-bearing models that have demonstrated the rapid uptake of copper-64. The radiationdoseestimates for man indicate that the intravenous administration of 7.0 mCi would result in radiationdoses to the kidney of 9.8 to 10.5 rads with other organs receiving substantially less radiation. 5 refs., 3 tabs.

Ultraviolet-B radiation (UV-B, 280–320-nm wavelengths) doses were estimated for 1024 wetlands in six national parks: Acadia (Acadia), Glacier (Glacier), Great Smoky Mountains (Smoky), Olympic (Olympic), Rocky Mountain (Rocky), and Sequoia/Kings Canyon (Sequoia). Estimates were made using ground-based UV-B data (Brewer spectrophotometers), solar radiation models, GIS tools, field characterization of vegetative features, and quantification of DOC concentration and spectral absorbance. UV-B doseestimates were made for the summer solstice, at a depth of 1 cm in each wetland. The mean dose across all wetlands and parks was 19.3 W-h m−2 (range of 3.4–32.1 W-h m−2). The mean dose was lowest in Acadia (13.7 W-h m−2) and highest in Rocky (24.4 W-h m−2). Doses were significantly different among all parks. These wetland doses correspond to UV-B flux of 125.0 μW cm−2 (range 21.4–194.7 μW cm−2) based on a day length, averaged among all parks, of 15.5 h. Dissolved organic carbon (DOC), a key determinant of water-column UV-B flux, ranged from 0.6 (analytical detection limit) to 36.7 mg C L−1 over all wetlands and parks, and reduced potential maximal UV-B doses at 1-cm depth by 1%–87 %. DOC concentration, as well as its effect on dose, was lowest in Sequoia and highest in Acadia (DOC was equivalent in Acadia, Glacier, and Rocky). Landscape reduction of potential maximal UV-B doses ranged from zero to 77% and was lowest in Sequoia. These regional differences in UV-B wetland dose illustrate the importance of considering all aspects of exposure in evaluating the potential impact of UV-B on aquatic organisms.

A future goal of the U.S. space program is a commitment to the manned exploration and habitation of Mars. An important consideration of such missions is the exposure of crew members to the damaging effects of ionizing radiation from high-energy galactic cosmic ray fluxes and solar proton flares. The crew will encounter the most harmful radiation environment in transit to Mars from which they must be adequately protected. However, once on the planet's surface, the Martian environment should provide a significant amount of protection from free-space radiative fluxes. In current Mars scenario descriptions, the crew flight time to Mars is estimated to be anywhere from 7 months to over a year each way, with stay times on the surface ranging from 20 days to 2 years. To maintain dose levels below established astronaut limits, doseestimates need to be determined for the entire mission length. With extended crew durations on the surface anticipated, the characterization of the Mars radiation environment is important in assessing all radiation protection requirements. This synopsis focuses on the probable doses incurred by surface inhabitants from the transport of galactic cosmic rays and solar protons through the Mars atmosphere. PMID:11537609

In order to make an assessment of radiation risk during manned missions in space, it is necessary first to have as accurate an estimation as possible of the radiation environment within the spacecraft to which the astronauts will be exposed. Then, with this knowledge and the inclusion of body self-shielding, estimations can be made of absorbed doses for various body organs (skin, eye, blood-forming organs, etc.). A review is presented of our present knowledge of the radiation environments and absorbed doses expected for several space mission scenarios selected for our development of the new radiation protection guidelines. The scenarios selected are a 90-day mission at an altitude (450 km) and orbital inclinations (28.5°, 57° and 90°) appropriate for NASA's Space Station, a 15-day sortie to geosynchronous orbit and a 90-day lunar mission. All scenarios chosen yielded dose equivalents between five and ten rem to the blood forming organs if no large solar particle event were encountered. Such particle events could add considerable exposure particularly to the skin and eye for all scenarios except the one at 28.5° orbital inclination.

Radiationdose to organs of 100 adult patients undergoing lumbar spine (LS) radiography at a University Hospital have been assessed. Free in air kerma measurement using an ionization chamber was used for the patient dosimetry. Organ and effective dose to the patients were estimated using PCXMC (version 1.5) software. The organs that recorded significant dose due to LS radiography were lungs, stomach, liver, adrenals, kidney, pancreas, spleen, galbladder, and the heart. It was observed that the stomach recorded the highest dose (48.2 ± 1.2 μGy) for LS anteroposterior (AP). The spleen also recorded the highest dose (41.2 ± 0.5 μGy) for LS lateral (LAT). The mean entrance surface air kerma (ESAK) of LS LAT (122.2 μGy) was approximately twice that of LS AP (76.3 μGy), but the effective dose for both examinations were approximately the same (LS LAT = 8.6 μSv and LS AP = 10.4 μSv). The overall stochastic health effect of radiation to patients due to LS radiography in the University Hospital is independent of the projection of the examination (AP or LAT). PMID:24672153

Patients undergoing cardiac catheterization are potentially at risk of radiation-induced health effects from the interventional fluoroscopic X-ray imaging used throughout the clinical procedure. The amount of radiation exposure is highly dependent on the complexity of the procedure and the level of optimization in imaging parameters applied by the clinician. For cardiac catheterization, patient radiation dosimetry, for key organs as well as whole-body effective, is challenging due to the lack of fixed imaging protocols, unlike other common X-ray based imaging modalities. Pediatric patients are at a greater risk compared to adults due to their greater cellular radio-sensitivities as well as longer remaining life-expectancy following the radiation exposure. In terms of radiation dosimetry, they are often more challenging due to greater variation in body size, which often triggers a wider range of imaging parameters in modern imaging systems with automatic dose rate modulation. The overall objective of this dissertation was to develop a comprehensive method of radiationdoseestimation for pediatric patients undergoing cardiac catheterization. In this dissertation, the research is divided into two main parts: the Physics Component and the Clinical Component. A proof-of-principle study focused on two patient age groups (Newborn and Five-year-old), one popular biplane imaging system, and the clinical practice of two pediatric cardiologists at one large academic medical center. The Physics Component includes experiments relevant to the physical measurement of patient organ dose using high-sensitivity MOSFET dosimeters placed in anthropomorphic pediatric phantoms. First, the three-dimensional angular dependence of MOSFET detectors in scatter medium under fluoroscopic irradiation was characterized. A custom-made spherical scatter phantom was used to measure response variations in three-dimensional angular orientations. The results were to be used as angular dependence

For correct radiationdose assessment, it is important to take the posture into account. A computational phantom with moving arms and legs was previously developed to address this need. Further, an accompanying graphical user interface (GUI), called PIMAL, was developed to enable doseestimation using realistic postures in a user-friendly manner such that the analyst's time could be substantially reduced. The importance of the posture for correct doseestimation has been demonstrated with a few case studies in earlier analyses. The previous version of PIMAL was somewhat limited in its features (i.e., it contained only a hermaphrodite phantom model and allowed only isotropic source definition). Currently GUI is being further enhanced by incorporating additional phantom models, improving the features, and increasing the user friendliness in general. This paper describes recent updates to the PIMAL software. In this summary recent updates to the PIMAL software, which aims to perform radiation transport simulations for phantom models in realistic postures in a user-friendly manner, are described. In future work additional phantom models, including hybrid phantom models, will be incorporated. In addition to further enhancements, a library of input files for the case studies that have been analyzed to date will be included in the PIMAL.

A computational phantom with moving arms and legs and an accompanying graphical user interface, PIMAL, was previously developed to enable radiationdoseestimation for different postures in a user-friendly manner. This initial version of the software was useful in adjusting the posture, generating the corresponding MCNP input file, and performing the radiation transport simulations for dose calculations using MCNP5 or MCNPX. However, it only included one mathematical phantom model (hermaphrodite) and allowed only isotropic point sources. Recently, the software was enhanced by adding two more mathematical phantom models, a male and female, and the source features were enhanced significantly by adding internal and external source options in a pull-down menu. Although the initial version of the software included only a mathematical hermaphrodite phantom, the features and models in the software are constantly being enhanced by adding more phantoms as well as other options to enable dose assessment for different configurations/cases in a user-friendly manner. In this latest version of the software, ICRP's recently released reference male and female voxel phantoms are included in a pull-down menu. The male and female models are described using 7 and 14 million voxels, respectively. Currently, the software is being modified further to include the International Commission on Radiation Protection's (ICRP) reference male and female voxel phantoms. Additionally, some case studies are being implemented and included in a library of input files. This paper describes recent updates to the software.

The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable doseestimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net. PMID:26435777

The radiation is considered as a double edged sword, as its beneficial and detrimental effects have been demonstrated. The potential benefits are being exploited to its maximum by adopting safe handling of radionuclide stipulated by the regulatory agencies. While the occupational workers are monitored by personnel monitoring devices, for general publics, it is not a regular practice. However, it can be achieved by using biomarkers with a potential for the radiation triage and medical management. An ideal biomarker to adopt in those situations should be rapid, specific, sensitive, reproducible, and able to categorize the nature of exposure and could provide a reliable doseestimation irrespective of the time of the exposures. Since cytogenetic markers shown to have many advantages relatively than other markers, the origins of various chromosomal abnormalities induced by ionizing radiations along with dose-response curves generated in the laboratory are presented. Current status of the gold standard dicentric chromosome assay, micronucleus assay, translocation measurement by fluorescence in-situ hybridization and an emerging protein marker the γ-H2AX assay are discussed with our laboratory data. With the wide choice of methods, an appropriate assay can be employed based on the net. PMID:26435777

Time-dependent radiationdoseestimations during interplanetary space flights 1,2Dobynde M.I., 2,3Drozdov A.Y., 2,4Shprits Y.Y.1Skolkovo institute of science and technology, Moscow, Russia 2University of California Los Angeles, Los Angeles, USA 3Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics, Moscow, Russia4Massachusetts Institute of Technology, Cambridge, USASpace radiation is the main restriction for long-term interplanetary space missions. It induces degradation of external components and propagates inside providing damage to internal environment. Space radiation particles and induced secondary particle showers can lead to variety of damage to astronauts in short- and long- term perspective. Contribution of two main sources of space radiation- Sun and out-of-heliosphere space varies in time in opposite phase due to the solar activity state. Currently the only habituated mission is the international interplanetary station that flights on the low Earth orbit. Besides station shell astronauts are protected with the Earth magnetosphere- a natural shield that prevents significant damage for all humanity. Current progress in space exploration tends to lead humanity out of magnetosphere bounds. With the current study we make estimations of spacecraft parameters and astronauts damage for long-term interplanetary flights. Applying time dependent model of GCR spectra and data on SEP spectra we show the time dependence of the radiation in a human phantom inside the shielding capsule. We pay attention to the shielding capsule design, looking for an optimal geometry parameters and materials. Different types of particles affect differently on the human providing more or less harm to the tissues. Incident particles provide a large amount of secondary particles while propagating through the shielding capsule. We make an attempt to find an optimal combination of shielding capsule parameters, namely material and thickness, that will effectively decrease

In keeping with the increasing utilization of CT examinations, the greater concern about radiation hazards from examinations has been addressed. In this regard, CT radiationdose optimization has been given a great deal of attention by radiologists, referring physicians, technologists, and physicists. Dose-saving strategies are continuously evolving in terms of imaging techniques as well as dose management. Consequently, regular updates of this issue are necessary especially for radiologists who play a pivotal role in this activity. This review article will provide an update on how we can optimize CT dose in order to maximize the benefit-to-risk ratio of this clinically useful diagnostic imaging method. PMID:22247630

Because many cancer patients are diagnosed earlier and live longer than in the past, second cancers induced by radiation therapy have become a clinically significant issue. An earlier biologically based model that was designed to estimate risks of high-doseradiation induced solid cancers included initiation of stem cells to a premalignant state, inactivation of stem cells at high radiationdoses, and proliferation of stem cells during cellular repopulation after inactivation. This earlier model predicted the risks of solid tumors induced by radiation therapy but overestimated the corresponding leukemia risks. Methods: To extend the model to radiation-induced leukemias, we analyzed in addition to cellular initiation, inactivation, and proliferation a repopulation mechanism specific to the hematopoietic system: long-range migration through the blood stream of hematopoietic stem cells (HSCs) from distant locations. Parameters for the model were derived from HSC biologic data in the literature and from leukemia risks among atomic bomb survivors v^ ho were subjected to much lower radiationdoses. Results: Proliferating HSCs that migrate from sites distant from the high-dose region include few preleukemic HSCs, thus decreasing the high-dose leukemia risk. The extended model for leukemia provides risk estimates that are consistent with epidemiologic data for leukemia risk associated with radiation therapy over a wide dose range. For example, when applied to an earlier case-control study of 110000 women undergoing radiotherapy for uterine cancer, the model predicted an excess relative risk (ERR) of 1.9 for leukemia among women who received a large inhomogeneous fractionated external beam dose to the bone marrow (mean = 14.9 Gy), consistent with the measured ERR (2.0, 95% confidence interval [CI] = 0.2 to 6.4; from 3.6 cases expected and 11 cases observed). As a corresponding example for brachytherapy, the predicted ERR of 0.80 among women who received an inhomogeneous low-dose

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

The Langley cosmic ray transport code and the Langley nucleon transport code (BRYNTRN) are used to quantify the transport and attenuation of galactic cosmic rays (GCR) and solar proton flares through the Martian atmosphere. Surface doses are estimated using both a low density and a high density carbon dioxide model of the atmosphere which, in the vertical direction, provides a total of 16 g/sq cm and 22 g/sq cm of protection, respectively. At the Mars surface during the solar minimum cycle, a blood-forming organ (BFO) dose equivalent of 10.5 to 12 rem/yr due to galactic cosmic ray transport and attenuation is calculated. Estimates of the BFO dose equivalents which would have been incurred from the three large solar flare events of August 1972, November 1960, and February 1956 are also calculated at the surface. Results indicate surface BFO dose equivalents of approximately 2 to 5, 5 to 7, and 8 to 10 rem per event, respectively. Doses are also estimated at altitudes up to 12 km above the Martian surface where the atmosphere will provide less total protection.

Background. Although radiation exposure is of great concern to expecting patients, little information is available on the fetal radiationdose associated with prophylactic internal iliac artery balloon occlusion (IIABO). Here we estimated the fetal radiationdose associated with prophylactic IIABO in Caesarean section (CS). Cases. We report our experience with the IIABO procedure in three consecutive patients with suspected placenta previa/accreta. Fetal radiationdose measurements were conducted prior to each CS by using an anthropomorphic phantom. Based on the simulated value, we calculated the fetal radiationdose as the absorbed dose. We found that the fetal radiationdoses ranged from 12.88 to 31.6 mGy. The fetal radiationdose during the prophylactic IIABOs did not exceed 50 mGy. Conclusion. The IIABO procedure could result in a very small increase in the risk of harmful effects to the fetus. PMID:26180648

The operation of Triga 2000 reactor in Nuclear Technology Center for Materials and Radiometry (PTNBR BATAN) normally produce tritium radionuclide which is the activation product of deuterium atom in reactor primary cooling water. According to previous monitoring, tritium was detected with the concentration of 8.236{+-}0.677 kBq/L and 1.704{+-}0.046 Bq/L in the primary cooling water and in reactor hall air, respectively. The tritium in reactor hall air chronically can be inhaled by the workers. In this research, tritium content in radiation workers' urine was determined to estimate the internal radiationdoses received by the workers. About 50-100 mL of urine samples were collected from 48 PTNBR workers that is classified as 24 radiation workers and 24 administration staffs as a control. Urine samples of 25 mL were then prepared by active charcoal and KMnO{sub 4} addition and followed with complete distillation. The 2 mL of distillate was added with 13 mL scintillator, shaked vigorously and remained in cool and dark condition for about 24 hours. The tritium in the samples was then measured using liquid scintillation counter (LSC) for 1 hour. From the measurement results it was obtained that the tritium concentration in the urine of radiation workers were in the range of not detected and 5.191 Bq/mL, whereas in the administration staffs the concentration were between not detected and 4.607 Bq/mL. Internally radiationdoses were calculated using the tritium concentration data, and it was found the averages about 0.602 {mu}Sv/year and 0.532 {mu}Sv/year for radiation workers and administration staffs, respectively. The doses received by the workers were lower than that of the permissible doses from tritium, i.e. 40 {mu}Sv/year.

The operation of Triga 2000 reactor in Nuclear Technology Center for Materials and Radiometry (PTNBR BATAN) normally produce tritium radionuclide which is the activation product of deuterium atom in reactor primary cooling water. According to previous monitoring, tritium was detected with the concentration of 8.236±0.677 kBq/L and 1.704±0.046 Bq/L in the primary cooling water and in reactor hall air, respectively. The tritium in reactor hall air chronically can be inhaled by the workers. In this research, tritium content in radiation workers' urine was determined to estimate the internal radiationdoses received by the workers. About 50-100 mL of urine samples were collected from 48 PTNBR workers that is classified as 24 radiation workers and 24 administration staffs as a control. Urine samples of 25 mL were then prepared by active charcoal and KMnO4 addition and followed with complete distillation. The 2 mL of distillate was added with 13 mL scintillator, shaked vigorously and remained in cool and dark condition for about 24 hours. The tritium in the samples was then measured using liquid scintillation counter (LSC) for 1 hour. From the measurement results it was obtained that the tritium concentration in the urine of radiation workers were in the range of not detected and 5.191 Bq/mL, whereas in the administration staffs the concentration were between not detected and 4.607 Bq/mL. Internally radiationdoses were calculated using the tritium concentration data, and it was found the averages about 0.602 μSv/year and 0.532 μSv/year for radiation workers and administration staffs, respectively. The doses received by the workers were lower than that of the permissible doses from tritium, i.e. 40 μSv/year.

Background radiationdose is used in dosimetry for estimating occupational doses of radiation workers or determining radiationdose of an individual following accidental exposure. In the present study, the absorbed dose and the background radiation level are determined using the electron spin resonance (ESR) method on tooth samples. The effect of using different tooth surfaces and teeth exposed with single medical X-rays on the absorbed dose are also evaluated. A total of 48 molars of position 6-8 were collected from 13 district hospitals in Peninsular Malaysia. Thirty-six teeth had not been exposed to any excessive radiation, and 12 teeth had been directly exposed to a single X-ray dose during medical treatment prior to extraction. There was no significant effect of tooth surfaces and exposure with single X-rays on the measured absorbed dose of an individual. The mean measured absorbed dose of the population is 34 ± 6.2 mGy, with an average tooth enamel age of 39 years. From the slope of a regression line, the estimated annual background dose for Peninsular Malaysia is 0.6 ± 0.3 mGy y(-1). This value is slightly lower than the yearly background dose for Malaysia, and the radiation background dose is established by ESR tooth measurements on samples from India and Russia. PMID:21404066

Myelotoxicity is the dose-limiting factor in radioimmunotherapy. Traditional methods most commonly used to estimate the radiation adsorbed dose to the bone marrow of patients consider contribution from radionuclide in the blood and/or total body. Targeted therapies, such as radioimmunotherapy, add a third potential source for radiation to the bone marrow because the radiolabeled targeting molecules can accumulate specifically on malignant target cells infiltrating the bone marrow. A non-invasive method for estimating the radiation absorbed dose to the red marrow of patients who have received radiolabeled monoclonal antibodies (MoAb) has been developed and explored. The method depends on determining the cumulated activity in three contributing sources: (1) marrow; (2) blood; and (3) total body. The novel aspect of this method for estimating marrow radiationdose is derivation of the radiationdose for the entire red marrow from radiationdoseestimates obtained by detection of cumulated activity in three lumbar vertebrae using a gamma camera. Contributions to the marrow radiationdose form marrow, blood, and total body cumulated activity were determined for patients who received an I-131 labeled MoAb, Lym-1, that reacts with malignant B-lymphocytes of chronic lymphocytic leukemia and nonHodgkin`s lymphoma. Six patients were selected for illustrative purposes because their vertebrae were readily visualized on lumbar images. 32 refs., 6 figs., 1 tab.

There is growing interest in the ability to monitor, track, and report exposure to radiation from medical imaging. Historically, however, dose information has been stored on an image-based dose sheet, an arrangement that precludes widespread indexing. Although scanner manufacturers are beginning to include dose-related parameters in the Digital Imaging and Communications in Medicine (DICOM) headers of imaging studies, there remains a vast repository of retrospective computed tomographic (CT) data with image-based dose sheets. Consequently, it is difficult for imaging centers to monitor their doseestimates or participate in the American College of Radiology (ACR) Dose Index Registry. An automated extraction software pipeline known as RadiationDose Intelligent Analytics for CT Examinations (RADIANCE) has been designed that quickly and accurately parses CT dose sheets to extract and archive dose-related parameters. Optical character recognition of information in the dose sheet leads to creation of a text file, which along with the DICOM study header is parsed to extract dose-related data. The data are then stored in a relational database that can be queried for dose monitoring and report creation. RADIANCE allows efficient dose analysis of CT examinations and more effective education of technologists, radiologists, and referring physicians regarding patient exposure to radiation at CT. RADIANCE also allows compliance with the ACR's dose reporting guidelines and greater awareness of patient radiationdose, ultimately resulting in improved patient care and treatment. PMID:21969661

Since August 1996, a dose reconstruction model has been conducted with thermoluminescent dosimeter (TLD)-embedded chains, belts and badges for external dose measurements on the residents in radiation-contaminated buildings. The TLD dosimeters, worn on the front of the torso, would not be adequate for dose measurement in cases when the radiation is anisotropic or the incident angles of radiation sources are not directed in the front-to-back direction. The shielding and attenuation by the body would result in the dose equivalent estimation being somewhat skewed. An organ doseestimation method with a Rando phantom under various exposure geometries is proposed. The conversion factors, obtained from the phantom study, may be applicable to organ doseestimations for residents in the contaminated buildings if the incident angles correspond to the phantom simulation results. There is a great demand for developing a mathematical model or Monte Carlo calculation to deal with complicated indoor layout geometry problems involving ionizing radiation. Further research should be directed toward conducting laboratory simulation by investigating the relationship between doses delivered from multiple radiation sources. It is also necessary to collaborate with experimental biological dosimetry, such as chromosome aberration analysis, fluorescence in situ hybridization (FISH) and retrospective ESR-dosimetry with teeth, applied to the residents, so that the organ dose equivalent estimations may be more reliable for radio-epidemiological studies. PMID:10214706

OBJECTIVE. The purpose of this study was to comprehensively study estimatedradiationdoses for subjects included in the main analysis of the Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography (CORE320) study ( ClinicalTrials.gov identifier NCT00934037), a clinical trial comparing combined CT angiography (CTA) and perfusion CT with the reference standard catheter angiography plus myocardial perfusion SPECT. SUBJECTS AND METHODS. Prospectively acquired data on 381 CORE320 subjects were analyzed in four groups of testing related to radiation exposure. Radiationdoseestimates were compared between modalities for combined CTA and perfusion CT with respect to covariates known to influence radiation exposure and for the main clinical outcomes defined by the trial. The final analysis assessed variations in radiationdose with respect to several factors inherent to the trial. RESULTS. The mean radiationdoseestimate for the combined CTA and perfusion CT protocol (8.63 mSv) was significantly (p < 0.0001 for both) less than the average dose delivered from SPECT (10.48 mSv) and the average dose from diagnostic catheter angiography (11.63 mSv). There was no significant difference in estimated CTA-perfusion CT radiationdose for subjects who had false-positive or false-negative results in the CORE320 main analyses in a comparison with subjects for whom the CTA-perfusion CT findings were in accordance with the reference standard SPECT plus catheter angiographic findings. CONCLUSION. Radiationdoseestimates from CORE320 support clinical implementation of a combined CT protocol for assessing coronary anatomy and myocardial perfusion. PMID:25539270

Videofluoroscopic swallowing study (VFSS) is considered the standard diagnostic imaging technique to investigate swallowing disorders and dysphagia. Few studies have been reported concerning the dose of radiation a patient receives and the scattering radiationdose received by a physician during VFSS. In this study, we investigated the dose of radiation (entrance skin dose, ESD) estimated to be received by a patient during VFSS using a human phantom (via a skin-dose monitor sensor placed on the neck of the human phantom). We also investigated the effective dose (ED) and dose equivalent (DE) received by a physician (wearing two personal dosimeters) during an actual patient procedure. One dosimeter (whole body) was worn under a lead apron at the chest, and the other (specially placed to measure doses received by the lens of the eye) outside the lead apron on the neck collar to monitor radiationdoses in parts of the body not protected by the lead apron. The ESD for the patient was 7.8 mGy in 5 min. We estimated the average patient dose at 12.79 mGy per VFSS procedure. The physician ED and DE during VFSS were 0.9 mSv/year and 2.3 mSv/year, respectively. The dose of radiation received by the physician in this study was lower than regulatory dose limits. However, in accordance with the principle that radiation exposure should be as low as reasonably achievable, every effort should be made (e.g., wearing lead glasses) to reduce exposure doses. PMID:27318941

The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiationdose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiationdoses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiationdose rate to biota to the U.S. Department of Energy`s (DOE`s) recommended dose rate limit of 0.4 mGy h{sup {minus}1} (1 rad d{sup {minus}1}). A dose rate no greater than 0.4 mGy h{sup {minus}1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE`s recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiationdose rate of 0. 1 mGy h{sup {minus}1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be conducted.

The purpose of this question and answer report is to provide a clear, easy-to-understand explanation of revised radiationdoseestimates which workers are likely to receive over the course of the cleanup at Three Mile Island, Unit 2, and of the possible health consequences to workers of these new estimates. We will focus primarily on occupational dose, although pertinent questions about public health and safety will also be answered.

Administered dose of ionizing radiation during medical imaging is an issue of increasing concern for the patient, for the clinical community, and for respective regulatory bodies. CT radiationdose is currently estimated based on a set of very simplifying assumptions which do not take the actual body geometry and organ specific doses into account. This makes it very difficult to accurately report imaging related administered dose and to track it for different organs over the life of the patient. In this paper this deficit is addressed in a two-fold way. In a first step, the absorbed radiationdose in each image voxel is estimated based on a Monte-Carlo simulation of X-ray absorption and scattering. In a second step, the image is segmented into tissue types with different radio sensitivity. In combination this allows to calculate the effective dose as a weighted sum of the individual organ doses. The main purpose of this paper is to assess the feasibility of automatic organ specific doseestimation. With respect to a commercially applicable solution and respective robustness and efficiency requirements, we investigated the effect of dose sampling rather than integration over the organ volume. We focused on the thoracic anatomy as the exemplary body region, imaged frequently by CT. For image segmentation we applied a set of available approaches which allowed us to cover the main thoracic radio-sensitive tissue types. We applied the doseestimation approach to 10 thoracic CT datasets and evaluated segmentation accuracy and administered dose and could show that organ specific doseestimation can be achieved.

Ultraviolet radiation (UVR) has been suggested as a potential cause of population declines and increases in malformations in amphibians. This study indicates that the present distributions of amphibians in four western U.S. National Parks are not related to UVR exposure, and sugg...

The ultraviolet (UV) B wavelength range (280 nm to 320 nm) of solar radiation can be a significant biological stressor, and has been hypothesized to be partially responsible for amphibian declines and malformation. This hypothesis has been difficult to evaluate, in part, because ...

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. The Phantom Torso Experiment (PTE) of NASA s Operational Radiation Protection Program has provided the actual flight measurements of active and passive dosimeters which were placed throughout the phantom on STS-91 mission for 10 days and on ISS Increment 2 mission. For the PTE, the variation in organ doses, which is resulted by the absorption and the changes in radiation quality with tissue shielding, was considered by measuring doses at many tissue sites and at several critical body organs including brain, colon, heart, stomach, thyroid, and skins. These measurements have been compared with the organ dose calculations obtained from the transport models. Active TEPC measurements of lineal energy spectra at the surface of the PTE also provided the direct comparison of galactic cosmic ray (GCR) or trapped proton dose and dose equivalent. It is shown that orienting the phantom body as actual in ISS is needed for the direct comparison of the transport models to the ISS data. One of the most important observations for organ dose equivalent of effective doseestimates on ISS is the fractional contribution from trapped protons and GCR. We show that for most organs over 80% is from GCR. The improved estimation of effective doses for radiation cancer risks will be made with the resultant tissue weighting factors and the modified codes.

The natural and manmade radiation environments to be encountered during lunar and Mars missions are qualitatively summarized. The computational methods available to characterize the radiation environment produced by an operating nuclear propulsion system are discussed. Mission profiles and vehicle configurations are presented for a typical all-propulsive, fully reusable lunar mission and for a typical all-propulsive Mars mission. Estimates of crew location biological doses are developed for all propulsive maneuvers. Post-shutdown dose rates near the nuclear engine are estimated at selected mission times. 15 refs., 4 figs.

Background: The radiation dosimetric literature concerning the medical and non-medical personnel working in nuclear medicine departments are limited, particularly radiationdoses received by radiation worker in nuclear medicine department during positron emission tomography (PET) radiopharmaceutical injection process. This is of interest and concern for the personnel. Aim: To measure the radiationdose received by the staff involved in injection process of Fluorine-18 Fluorodeoxyglucose (FDG). Materials and Methods: The effective whole body doses to the radiation workers involved in injections of 1511 patients over a period of 10 weeks were evaluated using pocket dosimeter. Each patient was injected with 5 MBq/kg of F-18 FDG. The F18-FDG injection protocol followed in our department is as follows. The technologist dispenses the dose to be injected and records the pre-injection activity. The nursing staff members then secure an intravenous catheter. The nuclear medicine physicians/residents inject the dose on a rotation basis in accordance with ALARA principle. After the injection of the tracer, the nursing staff members flush the intravenous catheter. The person who injected the tracer then measures the post-injection residual dose in the syringe. Results: The mean effective whole body doses per injection for the staff were the following: Nurses received 1.44±0.22 μSv/injection (3.71±0.48 nSv/MBq), for doctors the dose values were 2.44±0.25 μSv/injection (6.29±0.49 nSv/MBq) and for technologists the doses were 0.61±0.10 μSv/injection (1.58±0.21 nSv/MBq). It was seen that the mean effective whole body dose per injection of our positron emission tomography/computed tomography (PET/CT) staff who were involved in the F18-FDG injection process was maximum for doctors (54.34% differential doses), followed by nurses (32.02% differential doses) and technologist (13.64% differential doses). Conclusion: This study confirms that low levels of radiationdose are

Coronary angiography (CA) procedure uses various angiographic projections to elicit detailed information of the coronary arteries with some steep projections involving high radiationdose to patients. This study intends to evaluate radiationdoses and estimated risk from angiographic projections during CA procedure performed using novel flat detector (FD) system with improved image processing and noise reduction techniques. Real-time monitoring of radiationdoses using kerma-area product (KAP) meter was performed for 140 patients using Philips Clarity FD system. The CA procedure involved seven standard projections, of which five were extensively selected by interventionalists. Mean fluoroscopic time (FT), KAP, and reference air kerma (Ka,r) for CA procedure were 3.24 min (0.5-10.51), 13.99Gycm2 (4.02-37.6), and 231.43 mGy (73.8-622.15), respectively. Effective dose calculated using Monte Carlo-based PCXMC software was found to be 4.9mSv. Left anterior oblique (LAO) 45° projection contributed the highest radiationdose (28%) of the overall KAP. Radiation-induced risk was found to be higher in females compared to males with increased risk of lung cancer. An increase of 10%-15% in radiationdose was observed when one or more additional projections were adopted along with the seven standard projections. A 14% reduction of radiationdose was achieved from novel FD system when low-dose protocol during fluoroscopy and medium-dose protocol during cine acquisitions were adopted, compared to medium-dose protocol. PMID:27167263

Purpose: Estimates of secondary cancer risk after radiotherapy are becoming more important for comparative treatment planning. Modern treatment planning systems provide accurate three-dimensional dose distributions for each individual patient. These data open up new possibilities for more precise estimates of secondary cancer incidence rates in the irradiated organs. We report a new method to estimate organ-specific radiation-induced cancer incidence rates. The concept of an organ equivalent dose (OED) for radiation-induced cancer assumes that any two dose distributions in an organ are equivalent if they cause the same radiation-induced cancer incidence. Methods and Materials: The two operational parameters of the OED concept are the organ-specific cancer incidence rate at low doses, which is taken from the data of the atomic bomb survivors, and cell sterilization at higher doses. The effect of cell sterilization in various organs was estimated by analyzing the secondary cancer incidence data of patients with Hodgkin's disease who were treated with radiotherapy in between 1962 and 1993. The radiotherapy plans used at the time the patients had been treated were reconstructed on a fully segmented whole body CT scan. The dose distributions were calculated in individual organs for which cancer incidence data were available. The model parameter that described cell sterilization was obtained by analyzing the dose and cancer incidence rates for the individual organs. Results: We found organ-specific cell radiosensitivities that varied from 0.017 for the mouth and pharynx up to 1.592 for the bladder. Using the two model parameters (organ-specific cancer incidence rate and the parameter characterizing cell sterilization), the OED concept can be applied to any three-dimensional dose distribution to analyze cancer incidence. Conclusion: We believe that the concept of OED presented in this investigation represents a first step in assessing the potential risk of secondary

The purpose of this report is to present a methodology for evaluating the potential for aquatic biota to incur effects from exposure to chronic low-level radiation in the environment. Aquatic organisms inhabiting an environment contaminated with radioactivity receive external radiation from radionuclides in water, sediment, and from other biota such as vegetation. Aquatic organisms receive internal radiation from radionuclides ingested via food and water and, in some cases, from radionuclides absorbed through the skin and respiratory organs. Dose rate equations, which have been developed previously, are presented for estimating the radiationdose rate to representative aquatic organisms from alpha, beta, and gamma irradiation from external and internal sources. Tables containing parameter values for calculating radiationdoses from selected alpha, beta, and gamma emitters are presented in the appendix to facilitate dose rate calculations. The risk of detrimental effects to aquatic biota from radiation exposure is evaluated by comparing the calculated radiationdose rate to biota to the U.S. Department of Energy's (DOE's) recommended dose rate limit of 0.4 mGy h{sup -1} (1 rad d{sup -1}). A dose rate no greater than 0.4 mGy h{sup -1} to the most sensitive organisms should ensure the protection of populations of aquatic organisms. DOE's recommended dose rate is based on a number of published reviews on the effects of radiation on aquatic organisms that are summarized in the National Council on Radiation Protection and Measurements Report No. 109 (NCRP 1991). The literature identifies the developing eggs and young of some species of teleost fish as the most radiosensitive organisms. DOE recommends that if the results of radiological models or dosimetric measurements indicate that a radiationdose rate of 0.1 mGy h{sup -1} will be exceeded, then a more detailed evaluation of the potential ecological consequences of radiation exposure to endemic populations should be

Statistical analyses of data from epidemiologic studies of workers exposed to radiation have been based on recorded annual radiationdoses. It is usually assumed that the annual dose values are known exactly, although it is generally recognized that the data contain uncertainty due to measurement error and bias. We propose the use of a probability distribution to describe an individual`s dose during a specific period of time. Statistical methods for estimating this dose distribution are developed. The methods take into account the ``measurement error`` that is produced by the dosimetry system, and the bias that was introduced by policies that lead to right censoring of small doses as zero. The method is applied to a sample of dose histories obtained from hard copy dosimetry records at Oak Ridge National Laboratory (ORNL). The result of this evaluation raises serious questions about the validity of the historical personnel dosimetry data that is currently being used in low-dose studies of nuclear industry workers. In particular, it appears that there was a systematic underestimation of doses for ORNL workers. This could result in biased estimates of dose-response coefficients and their standard errors.

After administration of I-131 to the female patient, the possibility of radiation exposure of the embryo/fetus exists if the patient becomes pregnant while radioiodine remains in the body. Fetal radiationdoseestimates for such cases were calculated. Doses were calculated for various maternal thyroid uptakes and time intervals between administration and conception, including euthyroid and hyperthyroid cases. The maximum fetal dose calculating was about 9.8E-03 mGy/MBq, which occurred with 100% maternal thyroid uptake and a 1 week interval between administration and conception. Placental crossover of the small amount of radioiodine remaining 90 days after conception was also considered. Such crossover could result in an additional fetal dose of 9.8E-05 mGy/MBq and a maximum fetal thyroid self dose of 3.5E-04 mGy/MBq.

The next stage of work has been to examine more closely the A-bomb leukemia data which provides the underpinnings of the risk estimation of CML in the above mentioned manuscript. The paper by Hoel and Li (Health Physics 75:241-50) shows how the linear-quadratic model has basic non-linearities at the low dose region for the leukemias including CML. Pierce et. al., (Radiation Research 123:275-84) have developed distributions for the uncertainty in the estimated exposures of the A-bomb cohort. Kellerer, et. al., (Radiation and Environmental Biophysics 36:73-83) has further considered possible errors in the estimated neutron values and with changing RBE values with dose and has hypothesized that the tumor response due to gamma may not be linear. We have incorporated his neutron model and have constricted new A-bomb doses based on his model adjustments. The Hoel and Li dose response analysis has also been applied using the Kellerer neutron dose adjustments for the leukemias. Finally, both Pierce's dose uncertainties and Kellerer neutron adjustments are combined as well as the varying RBE with dose as suggested by Rossi and Zaider and used for leukemia dose-response analysis. First the results of Hoel and Li showing a significantly improved fit of the linear-quadratic dose response by the inclusion of a threshold (i.e. low-dose nonlinearity) persisted. This work has been complete for both solid tumor as well as leukemia for both mortality as well as incidence data. The results are given in the manuscript described below which has been submitted to Health Physics.

A gross survey of data on Van Allen belt radiations, galactic cosmic radiation, and solar cosmic radiation is presented. On the basis of these data that are, in part, fragmentary and uncertain, upper and lower limits of rad doses under different amounts of mass shielding are estimated. The estimates are preliminary especially in the cases of chance encounter with solar flare protons. Generally, the relative biological effectiveness of the high energetic space radiations and their secondaries appear insufficiently known to give detailed biological or rem doses. The overall ionization dosage of the low level galactic cosmic radiation in free space is estimated to be even in solar minimum years equivalent to less than 50 rem/year or 1 rem/week. Mass shielding up to 80 g/cm2 would not reduce the ionization dosage but would shield against heavy primaries and heavy ionizing secondaries, thus reducing the biological dose. The flux of energetic protons in the maximum intensity zone of the inner Van Allen belt is by about four orders of magnitude higher, their energy and penetration power, of course, lower. A shield of 25 g/cm2 would reduce the dose rate from 20 rad/hour under 2 g/cm2 to 5 rad/hour. These proton dose rates and also the electron and X-radiationdose rates under some g/cm2 shielding of low z-number material will not constitute a radiation hazard for flights straight through the inner and outer belt in about two hours. Staying within the maximum of the inner belt for two days would, however, lead even within 25 g/cm2 depth of outer shield and body itself to a dose of 200 rad which is on the permissible limit. Extreme solar cosmic ray events or proton showers of high intensity and a duration of days occurred with a frequency of 1-4 per year during the last highly active cycle. For the penetrating, most intense high energy event of February 23, 1956, the dose within 25 g/cm2 is estimated to have been in the order of 50 rad. In most cases the dose decreased more

A method was developed to reconstruct the internal radiationdose to off-site individuals who were exposed to fallout from nuclear weapons tests at the Nevada Test Site (NTS). By this method, committed absorbed doses can be estimated for 22 target organs of persons in four age groups and for selected organs of the fetus. Ingestion doses are calculated by combining age-group dose factors and intakes specific for age group, test event, and location as calculated by the PATHWAY food-chain model. Inhalation doses are calculated by combining age-group dose factors and breathing rates, and time-integrated air concentrations that are derived from the ORERP Air-Quality Data Base. Doseestimates are calculated for the radionuclides that contribute significantly to the total dose; these number 20 via the ingestion pathway and 46 via the inhalation pathway. Internal doses to nonspecified individuals and nonspecified fetuses are being reconstructed for each location in the ORERP Town Data Base for which exposure rates and cloud-arrival times are listed. Examples of reconstructing internal dose are presented. This method will also be adapted to reconstruct internal doses from NTS fallout to specific individuals in accordance with the person's age, past residence, life-style, and living pattern.

A method was developed to reconstruct the internal radiationdose to off-site individuals who were exposed to fallout from nuclear weapons tests at the Nevada Test Site (NTS). By this method, committed absorbed doses can be estimated for 22 target organs of persons in four age groups and for selected organs of the fetus. Ingestion doses are calculated by combining age-group dose factors and intakes specific for age group, test event, and location as calculated by the PATHWAY food-chain model. Inhalation doses are calculated by combining age-group dose factors and breathing rates, and time-integrated air concentrations that are derived from the ORERP Air-Quality Data Base. Doseestimates are calculated for the radionuclides that contribute significantly to the total dose; these number 20 via the ingestion pathway and 46 via the inhalation pathway. Internal doses to nonspecified individuals and nonspecified fetuses are being reconstructed for each location in the ORERP Town Data Base for which exposure rates and cloud-arrival times are listed. Examples of reconstructing internal dose are presented. This method will also be adapted to reconstruct internal doses from NTS fallout to specific individuals in accordance with the person's age, past residence, life-style, and living pattern. PMID:2211124

Members of the public visiting hospitalized patients undergoing nuclear medicine procedures or brachytherapy are exposed to radiation emanating from the patient. The radiation protection staff at the hospital is responsible for ensuring that the doses to these visitors are kept as low as is reasonably achievable and are maintained below applicable regulatory limits. These limits are normally expressed in terms of the effective dose to the visitor. Direct measurement of the effective dose, however, is not feasible, and the use of a quantity that provides a reasonable estimate, referred to as a surrogate, is required. This study used Monte Carlo radiation transport calculations to examine the feasibility of using bedside survey results, in units of roentgens per hour, as a surrogate for estimating the effective dose to a person who may be present at the survey location. The Monte Carlo code used in this work was MCNP Version 5. In these calculations, both the patient and the visitor were modeled using modified Medical Internal RadiationDose anthropomorphic phantoms. Radioactive material that emitted monoenergetic photons was located in several of the patient's organs in turn, and the bedside exposure rates and the effective doses at the same location were calculated. The calculations were repeated for several visitor locations, both at bedside along the length of the bed, and at increasing distances from the bed. The ratios of the exposure rates to the effective dose rates at each location gave an indication of the utility of the exposure rate measurements in providing a reasonable estimate of the effective dose. The results indicated that the survey data provided estimates of the effective dose within recommended accuracy for many exposure situations, but underestimated the effective dose to the visitor for other situations, especially locations close to bedside and for lower energy radiations. Use of appropriate correction factors based on this work could improve

The aim of this study was to estimate the radiationdose due to intravenous injection of 2-[{sup 18}F]fluoro-2-deoxy-D-glucose (FDG) for infants studied with PET. The radioactivity concentration in the brain and bladder content was measured with PET to determine the cumulated activity in these organs in 21 infant FDG studies. The individual organ masses were estimated according to the whole-body and brain masses, and they were used to calculate the absorbed dose per unit cumulated activity (S values). For organs other than brain and bladder, the cumulated activity was defined from adult studies. For each individual patient, the absorbed dose to the brain, bladder wall and selected organs were calculated. An estimation of the effective dose was determined. Whole-body distribution of FDG in the infants differed from adults: a greater proportion of the injected activity accumulated into the brain (9% versus 7%) and less was excreted to urine (7% versus 20% respectively). The measured cumulated activity in the brain was 0.25 MBq {center_dot} h/MBq and in the bladder content 0.04 MBq {center_dot}h/MBq with a large individual variation in latter. The calculated absorbed dose was 0.24 mGy/MBq to the brain and 1.03 mGy/MBq to the bladder wall. The estimated effective dose was 0.43 mSv/MBq. The dose to the bladder wall was lower in infants as compared to adults with ordinary amounts of injected activity. The greater amount of activity remaining in the body may increase the dose to other organs. The effective dose was lower compared to adults and conventional nuclear medicine studies of infants. PET can be a valuable tool in pediatric nuclear medicine because of good resolution images, sensitive radiation measurement and a variety of tracers labeled with short-lived isotopes. 27 refs., 4 figs., 2 tabs.

A new method is described for calculating radiationdoses to benthic invertebrates from radionuclide concentrations in freshwater sediment. Both internal and external radiationdoses were estimated for all 14 principal radionuclides of the uranium-238 decay series. Sediments were collected from three sites downstream of a uranium mining operation in northern Saskatchewan, Canada. Sediments from two sites, located approximately 1.6 and 4.4 km downstream from mining operations, yielded absorbed doses to both larval midges, Chironomus tentans, and adult amphipods, Hyalella azteca, of 59-60 and 19 mGy/year, respectively, compared to 3.2 mGy/year for a nearby control site. External beta radiation from protactinium-234 (234Pa) and alpha radiation from uranium (U) contributed most of the dose at the impacted sites, whereas polonium-210 (210Po) was most important at the control site. If a weighting factor of 20 was employed for the greater biological effect of alpha vs. beta and gamma radiation, then total equivalent doses rose to 540-560 mGy/year at the site closest to uranium operations. Such equivalent doses are above the 360-mGy/year no-observed-effect level for reproductive effects in vertebrates from gamma radiation exposure. Data are not available to determine the effect of such doses on benthic organisms, but they are high enough to warrant concern. Detrimental effects have been observed in H. azteca at similar uranium concentration in laboratory toxicity tests, but it remains unclear whether the radiotoxicity or the chemotoxicity of uranium is responsible for these effects. PMID:11686646

Purpose: To determine the radiobiologic parameters for high-grade gliomas. Methods and Materials: The biologic effective dose concept is used to estimate the {alpha}/{beta} ratio and K (dose equivalent for tumor repopulation/d) for high-grade glioma patients treated in a randomized fractionation trial. The equivalent radiationdose of temozolomide (Temodar) chemotherapy was estimated from another randomized study. The method assumes that the radiotherapy biologic effective dose is proportional to the adjusted radiotherapy survival duration of high-grade glioma patients. Results: The median tumor {alpha}/{beta} and K estimate is 9.32 Gy and 0.23 Gy/d, respectively. Using the published surviving fraction after 2-Gy exposure (SF{sub 2}) data, and the above {alpha}/{beta} ratio, the estimated median {alpha} value was 0.077 Gy{sup -1}, {beta} was 0.009 Gy{sup -2}, and the cellular doubling time was 39.5 days. The median equivalent biologic effective dose of temozolomide was 11.03 Gy{sub 9.3} (equivalent to a radiationdose of 9.1 Gy given in 2-Gy fractions). Random sampling trial simulations based on a cure threshold of 70 Gy in high-grade gliomas have shown the potential increase in tumor cure with dose escalation. Partial elimination of hypoxic cells (by chemical hypoxic cell sensitizers or carbon ion therapy) has suggested that considerable gains in tumor control, which are further supplemented by temozolomide, are achievable. Conclusion: The radiobiologic parameters for human high-grade gliomas can be estimated from clinical trials and could be used to inform future clinical trials, particularly combined modality treatments with newer forms of radiotherapy. Other incurable cancers should be studied using similar radiobiologic analysis.

Nuclear radiation induce some changes to the structure of exposed materials. The main effect of ionizing radiation when interacting with optical materials is the occurrence of color centers, which are quantitatively proportional to the up-taken doses. In this paper, a relation between browning effect magnitude and dose values was found. Using this relation, the estimation of a gamma radiationdose can be done. By using two types of laser wavelengths (532 nm and 633 nm), the optical powers transmitted thru glass samples irradiated to different doses between 0 and 59.1 kGy, were measured and the associated optical browning densities were determined. The use of laser light gives the opportunity of using its particularities: monochromaticity, directionality and coherence. Polarized light was also used for enhancing measurements quality. These preliminary results bring the opportunity of using glasses as detectors for the estimation of the dose in a certain point in space and for certain energy, especially in particles accelerators experiments, where the occurred nuclear reactions are involving the presence of high gamma rays fields.

A model was developed using a Monte-Carlo radiation transport code, MCNPX, to estimate the additional radiation exposure to aircrew members during solar particle events. The model transports an extrapolated particle spectrum based on satellite measurements through the atmosphere to aircraft altitudes. This code produces the estimated flux at a specific altitude where radiationdose conversion coefficients are applied to convert the particle flux into effective and ambient dose-equivalent rates. A cut-off rigidity model accounts for the shielding effects of the Earth's magnetic field. Comparisons were made between the model predictions and actual flight measurements taken with various types of instruments used to measure the mixed radiation field during ground level enhancements (GLEs) 60 and 65. An anisotropy analysis that uses neutron monitor responses and the pitch angle distribution of energetic solar particles was used to identify particle anisotropy for a solar event in December 2006. In anticipation of future commercial use, a computer code has been developed to implement the radiationdose assessment model for routine analysis. PMID:24084521

During the first day after the explosion, the Chornobyl accident of April 26, 1986 exposed a few hundred emergency workers to high dose levels ranging up to 16 Gy, resulting in acute radiation syndrome. Subsequently, several hundred thousand cleanup workers were sent to the Chornobyl power plant to mitigate the consequences of the accident. Depending on the nature of the work to be carried out, the cleanup workers were sent for periods ranging from several minutes to several months. The average dose from external radiation exposure that was received by the cleanup workers was about 170 mGy in 1986 and decreased from year to year. The radiation exposure was mainly due to external irradiation from gamma-ray-emitting radionuclides and was relatively homogeneous over all organs and tissues of the body. To assess the possible health consequences of external irradiation at relatively low dose rates, the U.S. National Cancer Institute is involved in two studies of Chornobyl cleanup workers: (1) a study of cancer incidence and thyroid disease among Estonian, Latvian and Lithuanian workers, and (2) a study of leukemia and other related blood diseases among Ukrainian workers. After an overview of the sources of exposure and of the radiationdoses received by the cleanup workers, a description of the efforts made to estimate individual doses in the Baltic and Ukrainian studies is presented. PMID:16808604

Purpose: Current methods for estimating and reporting radiationdose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiationdose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller

SPECT imaging of the brain with I-123 iomazenil has shown avid uptake of the radioligand in a distribution consistent with benzodiazepine receptor binding. It was desirable to radiolabel this compound with a positron emitting radionuclide so that quantitation of the receptor density could be assessed with PET imaging. Radiationdoseestimates for C-11 iomazenil were calculated prior to obtaining Institutional Review Board approval of this procedure. A previously published multicompartmental model was used as the biological model for estimating residence times associated with the C-11 labeled iomazenil. According to this model, 85-90% is excreted in the urine and 10-15% in the feces. A dynamic, voiding urinary bladder model was utilized for activity excreted renally and the ICRP 30 gastrointestinal tract kinetic model was used for activity excreted via the hepatobiliary system. Absorbed doses from C-11 (I-123) iomazenil to the urinary bladder were calculated to be 0.099 mGy/MBq (0.19 mGy/MBq) for a 4.8 hour bladder voiding interval. Shortening the bladder voiding interval to 2.0 hours had little effect on the bladder wall dose (0.095 mGy/MBq). However, a 30-minute void interval was estimated to lower the bladder wall dose substantially (0.045 mGy/MBq). Absorbed dose to the kidney was higher for C-11 iomazenil (0.054 vs 0.031 mGy/MBq) than for I-123 iomazenil due to rapid, early renal excretion of this very short-lived positron emitter. Doses to the gastrointestinal tract were estimated to be 4- to 20-fold lower for C-11 iomazenil compared to I-123 iomazenil. Overall, labeling iomazenil with C-11 rather than I-123 greatly reduces the radiationdose, per unit administered, to all organs except the kidneys.

Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimateradiationdose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal doseestimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiationdose to the fetus.

A literature review of more than 200 stereotactic body radiation therapy spine articles from the past 20 years found only a single article that provided dose-volume data and outcomes for each spinal cord of a clinical dataset: the Gibbs 2007 article (Gibbs et al, 2007(1)), which essentially contains the first 100 stereotactic body radiation therapy (SBRT) spine treatments from Stanford University Medical Center. The dataset is modeled and compared in detail to the rest of the literature review, which found 59 dose tolerance limits for the spinal cord in 1-5 fractions. We partitioned these limits into a unified format of high-risk and low-risk dose tolerance limits. To estimate the corresponding risk level of each limit we used the Gibbs 2007 clinical spinal cord dose-volume data for 102 spinal metastases in 74 patients treated by spinal radiosurgery. In all, 50 of the patients were previously irradiated to a median dose of 40Gy in 2-3Gy fractions and 3 patients developed treatment-related myelopathy. These dose-volume data were digitized into the dose-volume histogram (DVH) Evaluator software tool where parameters of the probit dose-response model were fitted using the maximum likelihood approach (Jackson et al, 1995(3)). Based on this limited dataset, for de novo cases the unified low-risk dose tolerance limits yielded an estimated risk of spinal cord injury of ≤1% in 1-5 fractions, and the high-risk limits yielded an estimated risk of ≤3%. The QUANTEC Dmax limits of 13Gy in a single fraction and 20Gy in 3 fractions had less than 1% risk estimated from this dataset, so we consider these among the low-risk limits. In the previously irradiated cohort, the estimated risk levels for 10 and 14Gy maximum cord dose limits in 5 fractions are 0.4% and 0.6%, respectively. Longer follow-up and more patients are required to improve the risk estimates and provide more complete validation. PMID:27000514

The aim of this study was to estimate internal radiationdoses and lifetime cancer risk from food ingestion. Radiationdoses from food intake were calculated using the Korea National Health and Nutrition Examination Survey and the measured radioactivity of 134Cs, 137Cs, and 131I from the Ministry of Food and Drug Safety in Korea. Total number of measured data was 8,496 (3,643 for agricultural products, 644 for livestock products, 43 for milk products, 3,193 for marine products, and 973 for processed food). Cancer risk was calculated by multiplying the estimated committed effective dose and the detriment adjusted nominal risk coefficients recommended by the International Commission on Radiation Protection. The lifetime committed effective doses from the daily diet are ranged 2.957-3.710 mSv. Excess lifetime cancer risks are 14.4-18.1, 0.4-0.5, and 1.8-2.3 per 100,000 for all solid cancers combined, thyroid cancer, and leukemia, respectively. PMID:26770031

The aim of this study was to estimate internal radiationdoses and lifetime cancer risk from food ingestion. Radiationdoses from food intake were calculated using the Korea National Health and Nutrition Examination Survey and the measured radioactivity of (134)Cs, (137)Cs, and (131)I from the Ministry of Food and Drug Safety in Korea. Total number of measured data was 8,496 (3,643 for agricultural products, 644 for livestock products, 43 for milk products, 3,193 for marine products, and 973 for processed food). Cancer risk was calculated by multiplying the estimated committed effective dose and the detriment adjusted nominal risk coefficients recommended by the International Commission on Radiation Protection. The lifetime committed effective doses from the daily diet are ranged 2.957-3.710 mSv. Excess lifetime cancer risks are 14.4-18.1, 0.4-0.5, and 1.8-2.3 per 100,000 for all solid cancers combined, thyroid cancer, and leukemia, respectively. PMID:26770031

A conceptual manned mission to Mars is analyzed in order to estimate potential ionizing radiationdoses that may be incurred by crew members during the course of the mission. The scenario is set for a journey during the solar active period and includes a brief stay on the Martian surface. Propulsion is assumed to be provided by nuclear thermal rocket power, and estimates of the dose contributions from the reactors are included. However, due to effective shielding of the reactors by large propellant tanks, it is found that the incurred doses are principally due to the charged particle natural environment. Recent data (August-December 1989) for large solar proton events are used to simulate the flame environment, while standard models are used for the trapped particle and galactic cosmic ray contributions. Shield effectiveness for several candidate materials are investigated.

A conceptual manned mission to Mars is analyzed in order to estimate potential ionizing radiationdoses that may be incurred by crew members during the course of the mission. The scenario is set for a journey during the solar active period and includes a brief stay on the Martian surface. Propulsion is assumed to be provided by nuclear thermal rocket power, and estimates of the dose contributions from the reactors are included. However, due to effective shielding of the reactors by large propellant tanks, it is found that the incurred doses are principally due to the charged particle natural environment. Recent data (August-December 1989) for large solar proton events are used to simulate the flare environment, while standard models are used for the trapped particle and galactic cosmic ray contributions. Shield effectiveness for several candidate materials are investigated.

A phase I/II trial delivering a single fraction of BNCT using p-Boronophenylalanine-Fructose and epithermal neutrons at the the Brookhaven Medical Research Reactor was initiated in September 1994. The primary endpiont of the study was to evaluate the feasibility and safety of a given BNCT dose. The clinical outcome of the disease was a secondary endpoint of the study. The objective of this paper is to evaluate the correlation of the clinical outcome of patients to the estimatedradiationdose from BNCT.

Computed tomography (CT) has long been a powerful tool in the diagnosis of disease, identification of tumors and guidance of interventional procedures. With CT examinations comes the concern of radiation exposure and the associated risks. In order to properly understand those risks on a patient-specific level, organ dose must be quantified for each CT scan. Some of the most widely used organ doseestimates are derived from fixed tube current (FTC) scans of a standard sized idealized patient model. However, in current clinical practice, patient size varies from neonates weighing just a few kg to morbidly obese patients weighing over 200 kg, and nearly all CT exams are performed with tube current modulation (TCM), a scanning technique that adjusts scanner output according to changes in patient attenuation. Methods to account for TCM in CT organ doseestimates have been previously demonstrated, but these methods are limited in scope and/or restricted to idealized TCM profiles that are not based on physical observations and not scanner specific (e.g. don't account for tube limits, scanner-specific effects, etc.). The goal of this work was to develop methods to estimate organ doses to patients undergoing CT scans that take into account both the patient size as well as the effects of TCM. This work started with the development and validation of methods to estimate scanner-specific TCM schemes for any voxelized patient model. An approach was developed to generate estimated TCM schemes that match actual TCM schemes that would have been acquired on the scanner for any patient model. Using this approach, TCM schemes were then generated for a variety of body CT protocols for a set of reference voxelized phantoms for which TCM information does not currently exist. These are whole body patient models representing a variety of sizes, ages and genders that have all radiosensitive organs identified. TCM schemes for these models facilitated Monte Carlo-based estimates of fully

The present study presents the Hiroshima University Registry of atomic bomb survivors, of which the total number is about 270,000, and application of absorbed doses. From this registry, we picked up 49,102 survivors and applied organ doses based on the dosimetry system 1986 (DS86), which is named the Atomic Bomb Survivor 1993 Dose (ABS93D). The applied dose data are based on the tables listed in the DS86 final report such as the free-in-air kermas, the house shielding factors, and organ dose factors for the active bone marrow and the breast. Calculations for the 13 other organs provided in DS86 are possible. To obtained the organ doses for each survivor, it is necessary to obtain information concerning (1) place exposed, (2) whether they were shielded or not, and (3) age. ABS93D body transmission factors for active bone marrow for neutrons and gamma rays agreed with DS 86 to within a few percent. Of the survivors studied, 35, 123 of them were used for the relative risk estimation of leukemia mortality, adopting the same method as the Radiation Effects Research Foundation (RERF) for comparison. For the observation period from 1968 to 1989, the analyzed relative risks for leukemia mortality at 1 Gy by shielded kerm and by active bone marrow dose are 2.01 and 2.37, respectively, which are consistent with the RERF results. 11 refs., 1 fig., 3 tabs.

Absorbed doses and the dose distributions at important tissues and organs in an anthropomorphic phantom are measured using TLD under the TBI conditions. The dose for each tissue or organ is also estimated and monitored for TBI treatment. PMID:12583267

The development of in vivo EPR has made it feasible to perform tooth dosimetry measurements in situ, greatly expanding the potential for using this approach for immediate screening after radiation exposures. The ability of in vivo tooth dosimetry to provide estimates of absorbed dose has been established through a series of experiments using unirradiated volunteers with specifically irradiated molar teeth placed in situ within gaps in their dentition and in natural canine teeth of patients who have completed courses of radiation therapy for head and neck cancers. Multiple measurements in patients who have received radiation therapy demonstrate the expected heterogeneous dose distributions. Dose response curves have been generated using both populations and, using the current methodology and instrument, the standard error of prediction based on single 4.5 minute measurements is approximately 1.5 Gy for inserted molar teeth and between 2.0 and 2.5 Gy in the more irregularly shaped canine teeth. Averaging of independent measurements can reduce this error significantly to values near 1 Gy. Developments to reduce these errors are underway, focusing on geometric optimization of the resonators, detector positioning techniques, and optimal data averaging approaches. In summary, it seems plausible that the EPR dosimetry techniques will have an important role in retrospective dosimetry for exposures involving large numbers of individuals. PMID:20065702

Acid rain causes accelerated mobilization of many materials in soils. Natural and anthropogenic radionuclides, especially 226Ra and 137Cs, are among these materials. Okamoto is apparently the only researcher to date who has attempted to quantify the effect of acid rain on the "background" radiationdose to man. He estimated an increase in dose by a factor of 1.3 following a decrease in soil pH of 1 unit. We reviewed literature that described the effects of changes in pH on mobility and plant uptake of Ra and Cs. Generally, a decrease in soil pH by 1 unit will increase mobility and plant uptake by factors of 2 to 7. Thus, Okamoto's doseestimate may be too low. We applied several simulation models to confirm Okamoto's ideas, with most emphasis on an atmospherically driven soil model that predicts water and nuclide flow through a soil profile. We modeled a typical, acid-rain sensitive soil using meteorological data from Geraldton, Ontario. The results, within the range of effects on the soil expected from acidification, showed essentially direct proportionality between the mobility of the nuclides and dose. This supports some of the assumptions invoked by Okamoto. We conclude that a decrease in pH of 1 unit may increase the mobility of Ra and Cs by a factor of 2 or more. Our models predict that this will lead to similar increases in plant uptake and radiological dose to man. Although health effects following such a small increase in dose have not been statistically demonstrated, any increase in dose is probably undesirable. PMID:3203639

Acid rain causes accelerated mobilization of many materials in soils. Natural and anthropogenic radionuclides, especially 226Ra and 137Cs, are among these materials. Okamoto is apparently the only researcher to date who has attempted to quantify the effect of acid rain on the "background" radiationdose to man. He estimated an increase in dose by a factor of 1.3 following a decrease in soil pH of 1 unit. We reviewed literature that described the effects of changes in pH on mobility and plant uptake of Ra and Cs. Generally, a decrease in soil pH by 1 unit will increase mobility and plant uptake by factors of 2 to 7. Thus, Okamoto's doseestimate may be too low. We applied several simulation models to confirm Okamoto's ideas, with most emphasis on an atmospherically driven soil model that predicts water and nuclide flow through a soil profile. We modeled a typical, acid-rain sensitive soil using meteorological data from Geraldton, Ontario. The results, within the range of effects on the soil expected from acidification, showed essentially direct proportionality between the mobility of the nuclides and dose. This supports some of the assumptions invoked by Okamoto. We conclude that a decrease in pH of 1 unit may increase the mobility of Ra and Cs by a factor of 2 or more. Our models predict that this will lead to similar increases in plant uptake and radiological dose to man. Although health effects following such a small increase in dose have not been statistically demonstrated, any increase in dose is probably undesirable. PMID:3203639

Organ doses are important quantities in assessing the radiation risk. In the case of children, estimation of this risk is of particular concern due to their significant radiosensitivity and the greater health detriment. The purpose of this study is to estimate the organ doses to paediatric patients undergoing barium meal and micturating cystourethrography examinations by clinical measurements and Monte Carlo simulation. In clinical measurements, dose-area products (DAPs) were assessed during examination of 50 patients undergoing barium meal and 90 patients undergoing cystourethrography examinations, separated equally within three age categories: namely newborn, 1 year and 5 years old. Monte Carlo simulation of photon transport in male and female mathematical phantoms was applied using the MCNP5 code in order to estimate the equivalent organ doses. Regarding the micturating cystourethrography examinations, the organs receiving considerable amounts of radiationdoses were the urinary bladder (1.87, 2.43 and 4.7 mSv, the first, second and third value in the parentheses corresponds to neonatal, 1 year old and 5 year old patients, respectively), the large intestines (1.54, 1.8, 3.1 mSv), the small intestines (1.34, 1.56, 2.78 mSv), the stomach (1.46, 1.02, 2.01 mSv) and the gall bladder (1.46, 1.66, 2.18 mSv), depending upon the age of the child. Organs receiving considerable amounts of radiation during barium meal examinations were the stomach (9.81, 9.92, 11.5 mSv), the gall bladder (3.05, 5.74, 7.15 mSv), the rib bones (9.82, 10.1, 11.1 mSv) and the pancreas (5.8, 5.93, 6.65 mSv), depending upon the age of the child. DAPs to organ/effective doses conversion factors were derived for each age and examination in order to be compared with other studies.

Fresh whole eggs treated with ionizing radiation for Salmonellae control testing. The eggshell was then removed and examined by electron paramagnetic resonance (EPR) spectroscopy to determine if EPR could be used to (1) distinguish irradiated from unirradiated eggs and (2) assess the absorbed dose. No EPR signals were detected in unirradiated eggs, while strong signals were measurable for more than 200 days after irradiation. Although a number of EPR signals were measured, the most intense resonance (g = 2.0019) was used for dosimetry throughout the study. This signal was observed to increase linearly with dose (up to [approximately]6 kGy), which decayed [approximately]20% within the first 5 days after irradiation and remained relatively constant thereafter. The standard added-dose method was used to assess, retrospectively, the dose to eggs processed at 0.2, 0.7, and 1.4 kGy. Relatively good results were obtained when measurement was made on the day the shell was reirradiated; with this procedure estimates were better for shell processed at the lower doses.

The U.S. National Cancer Institute, in collaboration with the Belarusian Ministry of Health, is conducting a study of thyroid cancer and other thyroid diseases in a cohort of about 12,000 persons who were exposed to fallout from the Chernobyl accident in April 1986. The study subjects were 18 years old or younger at the time of exposure and resided in Belarus in the most contaminated areas of the Gomel and Mogilev Oblasts, as well as in the city of Minsk. All cohort members had at least one direct thyroid measurement made in April–June 1986. Individual data on residential history, consumption of milk, milk products and leafy vegetables as well as administration of stable iodine were collected for all cohort members by means of personal interviews conducted between 1996 and 2007. Based on the estimated 131I activities in the thyroids, which were derived from the direct thyroid measurements, and on the responses to the questionnaires, individual thyroid doses from intakes of 131I were reconstructed for all cohort members. In addition, radiationdoses to the thyroid were estimated for the following minor exposure pathways: (a) intake of short-lived 132I, 133I and 132Te by inhalation and ingestion; (b) external irradiation from radionuclides deposited on the ground; and (c) ingestion intake of 134Cs and 137Cs. Intake of 131I was the major pathway for thyroid exposure; its mean contribution to the thyroid dose was 92%. The thyroid doses from 131I intakes varied from 0.5 mGy to almost 33 Gy; the mean was estimated to be 0.58 Gy, while the median was 0.23 Gy. The reconstructed doses are being used to evaluate the risk of thyroid cancer and other thyroid diseases in the cohort. PMID:23560632

Monitoring of the radiation loading on cosmonauts requires calculation of absorbed dose dynamics with regard to the stay of cosmonauts in specific compartments of the space vehicle that differ in shielding properties and lack means of radiation measurement. The paper discusses different aspects of calculation modeling of radiation effects on human body organs and tissues and reviews the effective doseestimates for cosmonauts working in one or another compartment over the previous period of the International space station operation. It was demonstrated that doses measured by a real or personal dosimeters can be used to calculate effective dose values. Correct estimation of accumulated effective dose can be ensured by consideration for time course of the space radiation quality factor. PMID:26292419

During the last few years, worldwide attention has been directed towards the estimation of natural background radiation levels. Several environmental monitoring networks have been established for systematic data collection and exchange of information.In the present study, measurements of annual effective dose from terrestrial γ-rays are carried out at pre-selected sites within several Egyptian governorates by using a calibrated gas-filled GM-detector connected to a microcomputer system. Contribution of the secondary cosmic-rays, which is of prime importance at sea level, is achieved by carrying out computation based on theoretical considerations.Terrestrial effective dose in Egypt is found to be between 106 and 371 μSv/yr, meanwhile the computed cosmic rays contribution is 260-296 μSv/yr. Accordingly, the annual collective effective dose due to natural background radiation is about 27,253 Man Sv for the last Egyptian population count (1989) considering 0.8 and 0.2 indoor and outdoor occupancy factors.

A brief description is provided of the basic concepts related to 'internal dose' and how it differs from doses that result from radioactive materials and direct radiation outside of the body. The principles of radiationdose reconstruction, as applied to both internal and external doses, is discussed based upon a recent publication prepared by the US National Council on Radiation Protection and Measurements. Finally, ideas are introduced related to residual radioactive contamination in the environment that has resulted from the releases from the damaged reactors and also to the management of wastes that may be generated in both regional cleanup and NPP decommissioning.

A brief description is provided of the basic concepts related to 'internal dose' and how it differs from doses that result from radioactive materials and direct radiation outside of the body. The principles of radiationdose reconstruction, as applied to both internal and external doses, are discussed on the basis of a recent publication prepared by the US National Council on Radiation Protection and Measurements. Finally, ideas are introduced related to residual radioactive contamination in the environment that has resulted from the releases from damaged reactors and also to the management of wastes that may be generated in both regional cleanup and decommissioning of the Fukushima nuclear power plant. PMID:22395282

The somatic effects of concern in human populations exposed to low doses and low dose rates of ionizing radiations are those that may be induced by mutation in individual cells, singly or in small numbers. The most important of these is considered to be cancer induction. Current knowledge of the carcinogenic effect of radiation in man has been reviewed in two recent reports: the 1977 UNSCEAR Report; and the 1980 BEIR-III Report. Both reports emphasize that cancers of the breast, thyroid, hematopoietic tissues, lung, and bone can be induced by radiation. Other cancers, including the stomach, pancreas, pharynx, lymphatic, and perhaps all tissues of the body, may also be induced by radiation. Both reports calculate risk estimates in absolute and relative terms for low-dose, low-LET whole-body exposure, and for leukemia, breast cancer, thyroid cancer, lung cancer, and other cancers. These estimates derive from exposure and cancer incidence data at high doses and at high dose rates. There are no compelling scientific reasons to apply these values of risk to the very low doses and low dose rates of concern in human radiation protection. In the absence of reliable human data for calculating risk estimates, dose-response models have been constructed from extrapolations of animal data and high-dose-rate human data for projection of estimated risks at low doses and low dose rates. (ERB)

Background The purpose of this study is to explore how a patient's height and weight can be used to predict the effective dose to a reference phantom with similar height and weight from a chest abdomen pelvis computed tomography scan when machine-based parameters are unknown. Since machine-based scanning parameters can be misplaced or lost, a predictive model will enable the medical professional to quantify a patient's cumulative radiationdose. Methods One hundred mathematical phantoms of varying heights and weights were defined within an x-ray Monte Carlo based software code in order to calculate organ absorbed doses and effective doses from a chest abdomen pelvis scan. Regression analysis was used to develop an effective dose predictive model. The regression model was experimentally verified using anthropomorphic phantoms and validated against a real patient population. Results Estimates of the effective doses as calculated by the predictive model were within 10% of the estimates of the effective doses using experimentally measured absorbed doses within the anthropomorphic phantoms. Comparisons of the patient population effective doses show that the predictive model is within 33% of current methods of estimating effective dose using machine-based parameters. Conclusions A patient's height and weight can be used to estimate the effective dose from a chest abdomen pelvis computed tomography scan. The presented predictive model can be used interchangeably with current effective doseestimating techniques that rely on computed tomography machine-based techniques. PMID:22004072

A Polonium metabolic model was derived and incorporated into a Fortran algorithm which estimates the systemic radiationdose from {sup 210}Po when applied to occupational urine bioassay data. The significance of the dosesestimated are examined by defining the degree of uncertainty attached to them through comprehensive statistical testing procedures. Many parameters necessary for dosimetry calculations, were evaluated from metabolic studies of {sup 210}Po in non-human primates. Two tamarins and six baboons were injected intravenously with {sup 210}Po citrate. Excreta and blood samples were collected. Five of the baboons were sacrifice at times ranging from 1 day to 3 months post exposure. Complete necropsies were performed and all excreta and the majority of all skeletal and tissue samples were analyzed radiochemically for their {sup 210}Po content. The {sup 210}Po excretion rate in the baboon was more rapid than in the tamarin. The biological half-time of {sup 210}Po excretion in the baboon was approximately 15 days while in the tamarin, the {sup 210}Po excretion rate was in close agreement with the 50 day biological half-time predicted by ICRP 30. Excretion fractions of {sup 210}Po in the non-human primates were found to be markedly different from data reported elsewhere in other species, including man.

Advances in Computed Tomography (CT) technology have led to an increase in the modality's diagnostic capabilities and therefore its utilization, which has in turn led to an increase in radiation exposure to the patient population. As a result, CT imaging currently constitutes approximately half of the collective exposure to ionizing radiation from medical procedures. In order to understand the radiation risk, it is necessary to estimate the radiationdoses absorbed by patients undergoing CT imaging. The most widely accepted risk models are based on radiosensitive organ dose as opposed to whole body dose. In this research, radiosensitive organ dose was estimated using Monte Carlo based simulations incorporating detailed multidetector CT (MDCT) scanner models, specific scan protocols, and using patient models based on accurate patient anatomy and representing a range of patient sizes. Organ doseestimates were estimated for clinical MDCT exam protocols which pose a specific concern for radiosensitive organs or regions. These doseestimates include estimation of fetal dose for pregnant patients undergoing abdomen pelvis CT exams or undergoing exams to diagnose pulmonary embolism and venous thromboembolism. Breast and lung dose were estimated for patients undergoing coronary CTA imaging, conventional fixed tube current chest CT, and conventional tube current modulated (TCM) chest CT exams. The correlation of organ dose with patient size was quantified for pregnant patients undergoing abdomen/pelvis exams and for all breast and lung doseestimates presented. Novel dose reduction techniques were developed that incorporate organ location and are specifically designed to reduce close to radiosensitive organs during CT acquisition. A generalizable model was created for simulating conventional and novel attenuation-based TCM algorithms which can be used in simulations estimating organ dose for any patient model. The generalizable model is a significant contribution of this

The present study aims to evaluate the use of the fluorescence in situ hybridization (FISH) translocation assay for retrospective doseestimation of acute accidental exposure to radiation in the past. Reciprocal translocation analysis by FISH with three whole-chromosome probes was performed on normal peripheral blood samples. Samples were irradiated with 0-5Gy (60)Co γ-rays in vitro, and dose-effect curves were established. FISH-based translocation analyses for six accident victims were then performed, and biological doses were estimated retrospectively by comparison with the dose-effect curves. Reconstructed doses by FISH were compared with estimateddoses obtained by analysis of di-centrics performed soon after exposure, or with doseestimates from tooth-enamel electron paramagnetic resonance (EPR) data obtained at the same time as the FISH analysis. Follow-up FISH analyses for an adolescent victim were performed. Results showed that dose-effect curves established in the present study follow a linear-quadratic model, regardless of the background translocation frequency. Estimateddoses according to two dose-effect curves for all six victims were similar. FISH doseestimations of three adult victims exposed to accidental radiation less than a decade prior to analysis (3, 6, or 7 years ago) were consistent with those estimated with tooth-enamel EPR measurements or analyses of di-centrics. Estimateddoses of two other adult victims exposed to radiation over a decade prior to analysis (16 or 33 years ago) were underestimated and two to three times lower than the values obtained from analysis of di-centrics or tooth-enamel EPR. Follow-up analyses of the adolescent victim showed that dosesestimated by FISH analysis decrease rapidly over time. Therefore, the accuracy of doseestimates by FISH is acceptable only when analysis is performed less than 7 years after exposure. Measurements carried out more than a decade after exposure through FISH analysis resulted in

This study details the distribution and trends of doses due to occupational radiation exposure among radiation workers from participating medical institutions in Kenya, where monthly dose measurements were collected for a period of one year ranging from January to December in 2007. A total of 367 medical radiation workers were monitored using thermoluminescent dosemeters. They included radiologists (27%), oncologists (2%), dentists (4%), Physicists (5%), technologists (45%), nurses (4%), film processor technicians (3%), auxiliary staff (4%), and radiology office staff (5%). The average annual effective dose of all categories of staff was found to range from 1.19 to 2.52 mSv. This study formed the initiation stage of wider, comprehensive and more frequent monitoring of occupational radiation exposures and long-term investigations into its accumulation patterns in our country.

Purpose: To investigate the radiationdose for pediatric high pitch cardiac CTA Methods: A total of 14 cases were included in this study, with mean age of 6.2 years (ranges from 2 months to 15 years). Cardiac CTA was performed using a dual-source CT system (Definition Flash, Siemens). Tube voltage (70, 80 and 100kV) was chosen based on patient weight. All patients were scanned using a high-pitch spiral mode (pitch ranges from 2.5 to 3) with tube current modulation technique (CareDose4D, Siemens). For each case, the three dimensional dose distributions were calculated using a Monte Carlo software package (IMPACT-MC, CT Image GmbH). Scanning parameters of each exam, including tube voltage, tube current, beamshaping filters, beam collimation, were defined in the Monte Carlo calculation. Tube current profile along projection angles was obtained from projection data of each tube, which included data within the over-scanning range along z direction. The volume of lungs was segmented out with CT images (3DSlicer). Lung doses of all patients were calculated and compared with CTDIvol, DLP, and SSDE. Results: The average (range) of CTDIvol, DLP and SSDE of all patients was 1.19 mGy (0.58 to 3.12mGy), 31.54 mGy*cm (12.56 to 99 mGy*cm), 2.26 mGy (1.19 to 6.24 mGy), respectively. Radiationdose to the lungs ranged from 0.83 to 4.18 mGy. Lung doses correlated with CTDIvol, DLP and SSDE with correlation coefficients(k) at 0.98, 0.93, and 0.99. However, for the cases with CTDIvol less than 1mGy, only SSDE preserved a strong correlation with lung doses (k=0.83), while much weaker correlations were found for CTDIvol (k=0.29) and DLP (k=-0.47). Conclusion: Lung doses to pediatric patients during Cardiac CTA were estimated. SSDE showed the most robust correlation with lung doses in contrast to CTDIvol and DLP.

Purpose: To describe a new method to estimate the mean heart dose for Hodgkin lymphoma patients treated several decades ago, using delineation of the heart on radiation therapy simulation X-rays. Mean heart dose is an important predictor for late cardiovascular complications after Hodgkin lymphoma (HL) treatment. For patients treated before the era of computed tomography (CT)-based radiotherapy planning, retrospective estimation of radiationdose to the heart can be labor intensive. Methods and Materials: Patients for whom cardiac radiationdoses had previously been estimated by reconstruction of individual treatments on representative CT data sets were selected at random from a case–control study of 5-year Hodgkin lymphoma survivors (n=289). For 42 patients, cardiac contours were outlined on each patient's simulation X-ray by 4 different raters, and the mean heart dose was estimated as the percentage of the cardiac contour within the radiation field multiplied by the prescribed mediastinal dose and divided by a correction factor obtained by comparison with individual CT-based dosimetry. Results: According to the simulation X-ray method, the medians of the mean heart doses obtained from the cardiac contours outlined by the 4 raters were 30 Gy, 30 Gy, 31 Gy, and 31 Gy, respectively, following prescribed mediastinal doses of 25-42 Gy. The absolute-agreement intraclass correlation coefficient was 0.93 (95% confidence interval 0.85-0.97), indicating excellent agreement. Mean heart dose was 30.4 Gy with the simulation X-ray method, versus 30.2 Gy with the representative CT-based dosimetry, and the between-method absolute-agreement intraclass correlation coefficient was 0.87 (95% confidence interval 0.80-0.95), indicating good agreement between the two methods. Conclusion: Estimating mean heart dose from radiation therapy simulation X-rays is reproducible and fast, takes individual anatomy into account, and yields results comparable to the labor

The rapid increase in the use of radiology and related exams and procedures has led to a concomitant increase in associated radiation risk. An application for the iPhone and iPod Touch called 'Radiation Passport' is described, which provides radiationdoseestimates and associated cancer risks (non fatal and fatal) and serves as a method by which to track an individual's cumulative exposure. PMID:20362943

Radiation-dose awareness and optimization in CT can greatly benefit from a dosereporting system that provides radiationdose and cancer risk estimates specific to each patient and each CT examination. Recently, we reported a method for estimating patientspecific dose from pediatric chest CT. The purpose of this study is to extend that effort to patient-specific risk estimation and to a population of pediatric CT patients. Our study included thirty pediatric CT patients (16 males and 14 females; 0-16 years old), for whom full-body computer models were recently created based on the patients' clinical CT data. Using a validated Monte Carlo program, organ dose received by the thirty patients from a chest scan protocol (LightSpeed VCT, 120 kVp, 1.375 pitch, 40-mm collimation, pediatric body scan field-of-view) was simulated and used to estimate patient-specific effective dose. Risks of cancer incidence were calculated for radiosensitive organs using gender-, age-, and tissue-specific risk coefficients and were used to derive patientspecific effective risk. The thirty patients had normalized effective dose of 3.7-10.4 mSv/100 mAs and normalized effective risk of 0.5-5.8 cases/1000 exposed persons/100 mAs. Normalized lung dose and risk of lung cancer correlated strongly with average chest diameter (correlation coefficient: r = -0.98 to -0.99). Normalized effective risk also correlated strongly with average chest diameter (r = -0.97 to -0.98). These strong correlations can be used to estimate patient-specific dose and risk prior to or after an imaging study to potentially guide healthcare providers in justifying CT examinations and to guide individualized protocol design and optimization.

The Hybrid Inflatable DSH combined with electric propulsion and high power solar-electric power systems offer a near TRL-now solution to the space radiation crew dose problem that is an inevitable aspect of long term manned interplanetary flight. Spreading program development and launch costs over several years can lead to a spending plan that fits with NASA's current and future budgetary limitations, enabling early manned interplanetary operations with space radiationdose control, in the near future while biomedical research, nuclear electric propulsion and active shielding research and development proceed in parallel. Furthermore, future work should encompass laboratory validation of HZETRN calculations, as previous laboratory investigations have not considered large shielding thicknesses and the calculations presented at these thicknesses are currently performed via extrapolation.

Space radiation effects mitigation has been identified as one of the highest priority technology development areas for human space flight in the NASA Strategic Space Technology Investment Plan (Dec. 2012). In this paper we review the special features of space radiation that lead to severe constraints on long-term (more than 180 days) human flight operations outside Earth's magnetosphere. We then quantify the impacts of human space radiationdose limits on spacecraft engineering design and development, flight program architecture, as well as flight program schedule and cost. A new Deep Space Habitat (DSH) concept, the hybrid inflatable habitat, is presented and shown to enable a flexible, affordable approach to long term manned interplanetary flight today.

Operational radiation protection of workers during the dismantling of nuclear facilities is based on the same radiation protection principles as that applied in its exploitation period with the objective of ensuring proper implementation of the as-low-as-reasonably-achievable (ALARA) principle. These principles are: prior determination of the nature and magnitude of radiological risk; classification of workplaces and workers depending on the risks; implementation of control measures; monitoring of zones and working conditions, including, if necessary, individual monitoring. From the experiences and the lessons learned during the dismantling processes carried out in Spain, several important aspects in the practical implementation of these principles that directly influence and ensure an adequate prevention of exposures and the estimation of internal doses are pointed out, with special emphasis on the estimation of internal doses due to transuranic intakes. PMID:17951606

The estimate of absorbed dose to individual organs of a space crewmember is affected by the geometry of the anatomical model of the astronaut used in the radiation transport calculation. For astronaut dosimetry, NASA currently uses the computerized anatomical male (CAM) and computerized anatomical female (CAF) stylized phantoms to represent astronauts in its operational radiationdose analyses. These phantoms are available in one size and in two body positions. In contrast, the UF Hybrid Adult Male and Female (UFHADM and UFHADF) phantoms have organ shapes based on actual CT data. The surfaces of these phantoms are defined by non-uniform rational B-spline surfaces, and are thus flexible in terms of body morphometry and extremity positioning. In this study, UFHADM and UFHADF are scaled to dimensions corresponding to 5th, 50th, and 95th percentile (PCTL) male and female astronauts. A ray-tracing program is written in Visual Basic 2008, which is then used to create areal density maps for dose points corresponding to various organs within the phantoms. The areal density maps, along with appropriate space radiation spectra, are input into the NASA program couplet HZETRN/BRYNTRN, and organ doses are calculated. The areal density maps selected tissues and organs of the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared. In addition, the organ doses for the 5th, 50th, and 95th PCTL male and female phantoms are presented and compared to organ doses for CAM and CAF.

The purpose of this study was two-fold: (a) to measure the dose to the brain using clinical protocols at our institution, and (b) to develop a scanner-independent dosimetry method to estimate brain dose. Radiationdose was measured with a pediatric anthropomorphic phantom and MOSFET detectors. Six current neuroradiology protocols were used: brain, sinuses, facial bones, orbits, temporal bones, and craniofacial areas. Two different CT vendor scanners (scanner A and B) were used. Partial volume correction factors (PVCFs) were determined for the brain to account for differences between point doses measured by the MOSFETs and average organ dose. The CTDIvol and DLP for each protocol were recorded. The dose to the brain (mGy) for scanners A and B was 10.7 and 10.0 for the brain protocol, 7.8 and 3.2 for the sinus, 10.2 and 8.6 for the facial bones, 7.4 and 4.7 for the orbits and 1.6 and 1.9 for the temporal bones, respectively. On scanner A, the craniofacial protocol included a standard and high dose option; the dose measured for these exams was 3.9 and 16.9 mGy, respectively. There was only one craniofacial protocol on scanner B; the brain dose measured on this exam was 4.8 mGy. A linear correlation was found between DLP and brain dose with the conversion factors: 0.049 (R2 = 0.87), 0.046 (R2 = 0.89) for scanner A and B, and 0.048 (R2 = 0.89) for both scanners. The range of dose observed was between 1.8 and 16.9 mGy per scan. This suggests that brain doseestimates may be made from DLP.

The biological effects of tritium in humans need to be clarified, because the chances of humans becoming exposed to tritium beta radiation may increase with the development of the nuclear fusion reactor. To evaluate the biological effects of tritium, it is necessary to estimate exactly the absorbed dose from the tritium beta rays in the tissue. In many reports, the absorbed dose of HTO in the tissues is estimated from the tritium content in body fluid and dose calculations are customarily based upon the water content of soft tissues, which is taken to be 0.7 to 0.8. However, these methods may not show the exact absorbed dose in the organs. In the present study, the radioactivity of the critical tissues was measured directly using a sample oxidizer and the absorbed dose was calculated from the radioactivity of tritium in the tissues. Details on the method for calculation of the absorbed dose in tissues of the mouse is shown in this report. The results suggest that the absorbed dose should be obtained from the radioactivity in the tissues. PMID:3212298

The data collected in Hiroshima and Nagasaki during the past 40 years on the children of survivors of the atomic bombings and on the children of a suitable control population are analyzed on the basis of the newly revised estimates of radiationdoses. No statistically significant effects emerge with respect to eight different indicators. Since, however, it may confidently be assumed some mutations were induced, we have taken the data at face value and calculated the minimal gametic doubling doses of acute radiation for the individual indicators at various probability levels. An effort has also been made to calculate the most probable doubling dose for the indicators combined. The latter value is between 1.7 and 2.2 Sv. It is suggested the appropriate figure for chronic radiation would be between 3.4 and 4.5 Sv. These estimates suggest humans are less sensitive to the genetic effects of radiation than has been assumed on the basis of past extrapolations from experiments with mice.

The data collected in Hiroshima and Nagasaki during the past 40 years on the children of survivors of the atomic bombings and on the children of a suitable control population are analyzed on the basis of the newly revised estimates of radiationdoses. No statistically significant effects emerge with respect to eight different indicators. Since, however, it may confidently be assumed some mutations were induced, we have taken the data at face value and calculated the minimal gametic doubling doses of acute radiation for the individual indicators at various probability levels. An effort has also been made to calculate the most probable doubling dose for the indicators combined. The latter value is between 1.7 and 2.2 Sv. It is suggested the appropriate figure for chronic radiation would be between 3.4 and 4.5 Sv. These estimates suggest humans are less sensitive to the genetic effects of radiation than has been assumed on the basis of past extrapolations from experiments with mice. PMID:2339701

Background & objectives: There is a growing concern over the radiation exposure of patients from undergoing 18FDG PET/CT (18F-fluorodeoxyglucose positron emission tomography/computed tomography) whole body investigations. The aim of the present study was to study the kinetics of 18FDG distributions and estimate the radiationdose received by patients undergoing 18FDG whole body PET/CT investigations. Methods: Dynamic PET scans in different regions of the body were performed in 49 patients so as to measure percentage uptake of 18FDG in brain, liver, spleen, adrenals, kidneys and stomach. The residence time in these organs was calculated and radiationdose was estimated using OLINDA software. The radiationdose from the CT component was computed using the software CT-Expo and measured using computed tomography dose index (CTDI) phantom and ionization chamber. As per the clinical protocol, the patients were refrained from eating and drinking for a minimum period of 4 h prior to the study. Results: The estimated residence time in males was 0.196 h (brain), 0.09 h (liver), 0.007 h (spleen), 0.0006 h (adrenals), 0.013 h (kidneys) and 0.005 h (stomach) whereas it was 0.189 h (brain), 0.11 h (liver), 0.01 h (spleen), 0.0007 h (adrenals), 0.02 h (kidneys) and 0.004 h (stomach) in females. The effective dose was found to be 0.020 mSv/MBq in males and 0.025 mSv/MBq in females from internally administered 18FDG and 6.8 mSv in males and 7.9 mSv in females from the CT component. For an administered activity of 370 MBq of 18FDG, the effective dose from PET/CT investigations was estimated to be 14.2 mSv in males and 17.2 mSv in females. Interpretation & conclusions: The present results did not demonstrate significant difference in the kinetics of 18FDG distribution in male and female patients. The estimated PET/CT doses were found to be higher than many other conventional diagnostic radiology examinations suggesting that all efforts should be made to clinically justify and

The estimate of absorbed radiationdose from internal emitters provides the information required to assess the radiation risk associated with the administration of radiopharmaceuticals for medical applications. The MIRD (Medical Internal RadiationDose) system of dose calculation provides a systematic approach to combining the biologic distribution data and clearance data of radiopharmaceuticals and the physical properties of radionuclides to obtain doseestimates. This tutorial presents a review of the MIRD schema, the derivation of the equations used to calculate absorbed dose, and shows how the MIRD schema can be applied to estimatedose from radiopharmaceuticals used in nuclear medicine.

Estimation of the adsorbed radiationdose while flight journeys is a complex problem, which should be solved to get correct evaluation of equivalent effective doses and radiation risk assessment. Direct measurements of the adsorbed dose in the aircrafts during regional flights (3-10 hours) has shown that the radiation in the plane may increase 10-15 times (to 2-4 mSv/h) compared to the values on the surface of the Earth (0.2-0.5 mSv/h). Results of instrumental research confirmed by the other investigations. It is a fact that adsorbed doses per year while flight journeys are less than doses from medical tests. However, while flight journeys passengers get the same doses as nuclear power plant staff, people in zones of natural radiation anomalies and so should be evaluated. According to the authors' research, flight journeys are safe enough, when solar activity is normal and if we fly under altitude of 18 km (as usual, while intercontinental flights). Most of people travel by plane not so often, but if flight is lasting in dangerous periods of solar activity (powerful solar winds and magnetic field storms), passengers and flight crew can adsorb great amount of radiationdoses. People, who spend more than 500 hours in flight journeys (pilots, business oriented persons', government representatives, etc.) get amount of radiation, which can negatively influence on health and provoke diseases, such as cancer. Authors consider that problem actual and researches are still going on. It is revealed, that radiation can be calculated, using special equations. Great part of radiation depends on very variable outer-space component and less variable solar. Accurate calculations of doses will be possible, when we will take into account all features of radiation distribution (time, season of year and exact time of the day, duration of flight), technical features of aircraft and logistics of flight (altitude, latitude). Results of first attempts of radiationdoses modelling confirmed

The article is intended to give a short overview of epidemiological data on cancer risks associated with very low absorbed doses of ionising radiation. The linear no-threshold (LNT) approach to estimate cancer risks involves the use of epidemiological data at higher doses (>100 mSv), but is supported by data from lower exposure of more sensitive population groups like fetuses and children and the presence of rare types of cancer. The International Commission on Radiological Protection (ICRP) concludes that the LNT model, combined with a dose and dose-rate effectiveness (reduction) factor (DDREF) of 2 for extrapolation from high doses, should be used. The numerical value of the DDREF is challenged by the findings from some recent epidemiological studies demonstrating risks per unit dose compatible with the risks observed in the higher dose studies. In general there is very limited knowledge about the cancer risk after low absorbed doses (10-100 mSv), as most of epidemiological studies have limitations in detecting small excess risks arising from low doses of radiation against fluctuations in the influence of background risk factors. Even if there may be signiﬁcant deviations from linearity in the relevant dose range 0-100 mSv, one does not know the magnitude or even the direction of any such deviations. The risks could be lower than those predicted by a linear extrapolation, but they could also be higher. Until more results concerning the effects of low-dose exposure are available, a reasonable radiation protection approach is to consider the risk proportional to the dose. PMID:25802468

An example is described of Bayesian estimation of radiation absorbed dose thresholds (subsequently simply referred to as dose thresholds) using a specific parametric model applied to a data set on mice exposed to 60Co gamma rays and fission neutrons. A Weibull based relative risk model with a dose threshold parameter was used to analyse, as an example, lung cancer mortality and determine the posterior density for the threshold dose after single exposures to 60Co gamma rays or fission neutrons from the JANUS reactor at Argonne National Laboratory. The data consisted of survival, censoring times and cause of death information for male B6CF1 unexposed and exposed mice. The 60Co gamma whole-body doses for the two exposed groups were 0.86 and 1.37 Gy. The neutron whole-body doses were 0.19 and 0.38 Gy. Marginal posterior densities for the dose thresholds for neutron and gamma radiation were calculated with numerical integration and found to have quite different shapes. The density of the threshold for 60Co is unimodal with a mode at about 0.50 Gy. The threshold density for fission neutrons declines monotonically from a maximum value at zero with increasing doses. The posterior densities for all other parameters were similar for the two radiation types.

A high pure germanium detector-based gamma-ray spectroscopy low-background counting system was used to determine the levels of natural radioactivity from beach sand samples on the Egyptian coast along the Mediterranean and Red Seas. The activity concentrations of (226)Ra, (232)Th and (40)K were found to lie in the range of 30±11 to 60±14 Bq kg(-1) with a mean of 39±15 Bq kg(-1), 12±3 to 30±14 Bq kg(-1) with a mean of 21±13 Bq kg(-1) and 392±22 to 413±22 Bq kg(-1) with a mean of 402±23 Bq kg(-1), respectively. Radiation hazard indices and annual effective doses were evaluated and compared with the international data. The results indicate that the values obtained fall below the internationally accepted maximum limits and do not pose any significant radiation hazard to individuals in the study area. From these results, a radiological baseline map of Egyptian beaches can be drawn and used as reference information to assess any future alterations in the radioactivity of beach sands due to any changes in the sea sediments. PMID:21169289

This study was conducted to determine the estimatedradiationdoses that individuals in five nearby population groups and the general population in the surrounding area may have received as a consequence of activities at a uranium processing plant in Weldon Spring, Missouri. The study is retrospective and encompasses plant operations (1957-1966), cleanup (1967-1969), and maintenance (1969-1982). The doseestimates for members of the nearby population groups are as follows. Of the three periods considered, the largest doses to the general population in the surrounding area would have occurred during the plant operations period (1957-1966). Doseestimates for the cleanup (1967-1969) and maintenance (1969-1982) periods are negligible in comparison. Based on the monitoring data, if there was a person residing continually in a dwelling 1.2 km (0.75 mi) north of the plant, this person is estimated to have received an average of about 96 mrem/yr (ranging from 50 to 160 mrem/yr) above background during plant operations, whereas the dose to a nearby resident during later years is estimated to have been about 0.4 mrem/yr during cleanup and about 0.2 mrem/yr during the maintenance period. These values may be compared with the background dose in Missouri of 120 mrem/yr.

Radium applicators and pure beta emitters have been widely used in the past to treat skin haemangioma in early childhood. A well defined relationship between the low doses received from these applicators and radiation-induced cancers requires accurate dosimetry. A human-based CT scan phantom has been used to simulate every patient and treatment condition and then to calculate the source-target distance when radium and pure beta applicators were used. The effective transmission factor ϕ(r) for the gamma spectrum emitted by the radium sources applied on the skin surface was modelled using Monte Carlo simulations. The well-known quantization approach was used to calculate gamma doses delivered from radium applicators to various anatomical points. For 32P, 90Sr/90Y applicators and 90Y needles we have used the apparent exponential attenuation equation. The dose calculation algorithm was integrated into the ICTA software (standing for a model that constructs an Individualized phantom based on CT slices and Auxological data), which has been developed for epidemiological studies of cohorts of patients who received radium and beta-treatments for skin haemangioma. The ϕ(r) values obtained for radium skin applicators are in good agreement with the available values in the first 10 cm but higher at greater distances. Gamma doses can be calculated with this algorithm at 165 anatomical points throughout the body of patients treated with radium applicators. Lung heterogeneity and air crossed by the gamma rays are considered. Comparison of absorbed doses in water from a 10 mg equivalent radium source simulated by ICTA with those measured at the Radiumhemmet, Karolinska Hospital (RAH) showed good agreement, but ICTA estimation of organ doses did not always correspond those estimated at the RAH. Beta doses from 32P, 90Sr/90Y applicators and 90Y needles are calculated up to the maximum beta range (11 mm).

In preparation for measurement of regional cerebral oxygen metabolism by positron emission tomography, radiation absorbed doseestimates for 19 internal organs, blood, and total body were calculated for newborn infants following bolus intravenous administration of H2( V)O and brief inhalation of C VO and O VO. Cumulated activity for each radiopharmaceutical was calculated from a compartmental model based on the known biologic behavior of the compound. Values for mean absorbed dose/unit cumulated activity (S) for internal organs and total body were based on a newborn phantom. S was separately calculated for blood. Total radiopharmaceutical absorbed doseestimates necessary to measure cerebral oxygen metabolism in a 3.51-kg infant based on 0.7 mCi/kg H2( V)O and 1 mCi/kg C VO and O VO were determined to be 1.6 rad to the lung (maximum organ dose), 0.28 rad to the marrow, 0.46 rad to the gonads, and 0.22 rad to total body. These values are similar to those for current clinical nuclear medicine procedures employing /sup 99m/Tc in newborn infants.

Purpose. To estimate effective dose and organ equivalent doses of prospective ECG-triggered high-pitch CTCA. Materials and Methods. For dose measurements, an Alderson-Rando phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a second-generation dual-source scanner (SOMATOM Definition Flash, Siemens Medical Solutions, Germany). The following scan parameters were used: 320 mAs per rotation, 100 and 120 kV, pitch 3.4 for prospectively ECG-triggered high-pitch CTCA, scan range of 13.5 cm, collimation 64 × 2 × 0.6 mm with z-flying focal spot, gantry rotation time 280 ms, and simulated heart rate of 60 beats per minute. Results. Depending on the applied tube potential, the effective whole-body dose of the cardiac scan ranged from 1.1 mSv to 1.6 mSv and from 1.2 to 1.8 mSv for males and females, respectively. The radiosensitive breast tissue in the range of the primary beam caused an increased female-specific effective dose of 8.6%±0.3% compared to males. Decreasing the tube potential, a significant reduction of the effective dose of 35.8% and 36.0% can be achieved for males and females, respectively (P < 0.001). Conclusion. The radiologist and the CT technician should be aware of this new dose-saving strategy to keep the radiation exposure as low as reasonablly achievable. PMID:22701793

Functional kidney damage in mice was measured after a series of fractionated X-irradiations. Doses per fraction of 0.75-12.5 Gy were given as 2, 5, 10, 30, 40, 60, or 80 equal doses in a total treatment time of 4 weeks. Renal function (measured by clearance of /sup 51/CrEDTA or hematocrit levels) deteriorated progressively, in a dose related manner, from 20 to 46 weeks after the start of treatment. The changes in renal function versus time were fitted by a polynomial regression through all data and interpolated values for /sup 51/CrEDTA clearance were then calculated at 30 and 40 weeks after treatment. Steep dose response curves were obtained and these were used to calculate isoeffective doses for the different fractionation schedules. There was a marked increase in total isoeffective doses from 2-30 fractions and these data were well described by a linear quadratic (L.Q.) expression for damage with an alpha/beta ratio of 2.3 +/- 0.2 Gy. There was only a slight increase in the total isoeffect dose as the size of the dose per fraction was decreased below 2 Gy and the measured isoeffect doses after 40 to 80 fractions were lower than predicted on the basis of an L.Q. model assuming complete repair between successive irradiations. The flexure dose for mouse kidneys irradiated 3 times per day was, effectively, 1 to 2 Gy and hyperfractionation using lower doses per fraction did not lead to significant, additional repair.

In the development of new radiopharmaceuticals, animal studies are typically performed to get a first approximation of the expected radiationdose in humans. This study evaluates the performance of some commonly used data extrapolation techniques to predict residence times in humans using data collected from animals. Residence times were calculated using animal and human data, and distributions of ratios of the animal results to human results were constructed for each extrapolation method. Four methods using animal data to predict human residence times were examined: (1) using no extrapolation, (2) using relative organ mass extrapolation, (3) using physiological time extrapolation, and (4) using a combination of the mass and time methods. The residence time ratios were found to be log normally distributed for the nonextrapolated and extrapolated data sets. The use of relative organ mass extrapolation yielded no statistically significant change in the geometric mean or variance of the residence time ratios as compared to using no extrapolation. Physiologic time extrapolation yielded a statistically significant improvement (p < 0.01, paired t test) in the geometric mean of the residence time ratio from 0.5 to 0.8. Combining mass and time methods did not significantly improve the results of using time extrapolation alone. 63 refs., 4 figs., 3 tabs.

Estimates of both individual and collective doses received by the United States population following the Chernobyl accident have been made by using the data obtained from the U.S. Environmental Protection Agency's Environmental Radiation Ambient Monitoring System. Radionuclides associated with the debris first were measured in precipitation and surface air particulates at Portland, OR and Olympia, WA on 5 May 1986. Iodine-131 was the most consistently measured nuclide in all media, although several Cs and Ru isotopes also were observed. Strontium and any actinides notably were absent from the samples at the lower level of detection. The highest calculated individual-organ dose due to intake during May and June 1986 was 0.52 mSv to the infant thyroid in the state of Washington. This was predominantly (98%) from the ingestion of milk. The maximum U.S. collective dose equivalent to any organ was calculated to be 3,300 person-Sv to the thyroid. Risk estimates project three excess lung cancer deaths and an additional four deaths due to cancers of thyroid, breast and leukemia in the U.S. population over the next 45 y from exposure during the May-June 1986 interval. The only long-lived radionuclide measured in milk samples following the accident was 137Cs. We estimate 20 excess fatalities from the ingestion of 137Cs in milk during all subsequent years, with six of these due to lung cancer and the majority of the remainder distributed approximately equally among cancers of the thyroid, breast, liver and leukemia. A total of 100 excess fatalities from all dietary components was estimated. Because of the uncertainty of risk estimates from data such as those available for this study, all calculated values carry a range of uncertainty from a minimum of one-half the calculated value to a maximum of two times the calculated value.

At the direction of the Technical Steering Panel (TSP) of the Hanford Environmental Dose Reconstruction (HEDR) Project, Battelle staff have reviewed and analyzed available data regarding possible historical radiationdoses to individuals resulting from radionuclide releases to the Columbia River. The objective of this review was to recommend to the TSP the spatial and temporal scope and level of effort on Columbia River work to most effectively extend work performed in Phase I of the project (PNL 1991a, PNL 1991b) to meet the project objectives. A number of options were analyzed. Four stretches of the Columbia River and adjacent Pacific coastal waters were defined and investigated for four time periods. Radiationdoses arising from ten potentially major exposure pathways were evaluated for each of the time/location combinations, and several alternative methods were defined for estimating the doses from each pathway. Preliminary cost estimates were also developed for implementing doseestimation activities for each of the possible combinations.

At the direction of the Technical Steering Panel (TSP) of the Hanford Environmental Dose Reconstruction (HEDR) Project, Battelle staff have reviewed and analyzed available data regarding possible historical radiationdoses to individuals resulting from radionuclide releases to the Columbia River. The objective of this review was to recommend to the TSP the spatial and temporal scope and level of effort on Columbia River work to most effectively extend work performed in Phase I of the project (PNL 1991a, PNL 1991b) to meet the project objectives. A number of options were analyzed. Four stretches of the Columbia River and adjacent Pacific coastal waters were defined and investigated for four time periods. Radiationdoses arising from ten potentially major exposure pathways were evaluated for each of the time/location combinations, and several alternative methods were defined for estimating the doses from each pathway. Preliminary cost estimates were also developed for implementing doseestimation activities for each of the possible combinations.

To evaluate the environmental contamination and radiation exposure dose rates due to artificial radionuclides in Kawauchi Village, Fukushima Prefecture, the restricted area within a 30-km radius from the Fukushima Dai-ichi Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples, tree needles, and mushrooms were analyzed by gamma spectrometry. Nine months have passed since samples were collected on December 19 and 20, 2011, 9 months after the FNPP accident, and the prevalent dose-forming artificial radionuclides from all samples were 134Cs and 137Cs. The estimated external effective doses from soil samples were 0.42–7.2 µSv/h (3.7–63.0 mSv/y) within the 20-km radius from FNPP and 0.0011–0.38 µSv/h (0.010–3.3 mSv/y) within the 20–30 km radius from FNPP. The present study revealed that current levels are sufficiently decreasing in Kawauchi Village, especially in areas within the 20- to 30-km radius from FNPP. Thus, residents may return their homes with long-term follow-up of the environmental monitoring and countermeasures such as decontamination and restrictions of the intake of foods for reducing unnecessary exposure. The case of Kawauchi Village will be the first model for the return to residents’ homes after the FNPP accident. PMID:23049869

To evaluate the environmental contamination and radiation exposure dose rates due to artificial radionuclides in Kawauchi Village, Fukushima Prefecture, the restricted area within a 30-km radius from the Fukushima Dai-ichi Nuclear Power Plant (FNPP), the concentrations of artificial radionuclides in soil samples, tree needles, and mushrooms were analyzed by gamma spectrometry. Nine months have passed since samples were collected on December 19 and 20, 2011, 9 months after the FNPP accident, and the prevalent dose-forming artificial radionuclides from all samples were (134)Cs and (137)Cs. The estimated external effective doses from soil samples were 0.42-7.2 µSv/h (3.7-63.0 mSv/y) within the 20-km radius from FNPP and 0.0011-0.38 µSv/h (0.010-3.3 mSv/y) within the 20-30 km radius from FNPP. The present study revealed that current levels are sufficiently decreasing in Kawauchi Village, especially in areas within the 20- to 30-km radius from FNPP. Thus, residents may return their homes with long-term follow-up of the environmental monitoring and countermeasures such as decontamination and restrictions of the intake of foods for reducing unnecessary exposure. The case of Kawauchi Village will be the first model for the return to residents' homes after the FNPP accident. PMID:23049869

Coronary computed tomography (CT) angiography is associated with high radiationdose and this has raised serious concerns in the literature. Awareness of various parameters for doseestimates and measurements of coronary CT angiography plays an important role in increasing our understanding of the radiation exposure to patients, thus, contributing to the implementation of dose-saving strategies. This article provides an overview of the radiationdose quantity and its measurement during coronary CT angiography procedures. PMID:24392190

This report provides unit dose to concentration levels that may be used to develop control criteria for radionuclide activity in hazardous waste; if implemented, these criteria would be developed to provide an adequate level of public and worker health protection, for wastes regulated under U.S, Environmental Protection Agency (EPA) requirements (as derived from the Resource Conservation and Recovery Act [RCRA] and/or the Toxic Substances Control Act [TSCA]). Thus, DOE and the US Nuclear Regulatory Commission can fulfill their obligation to protect the public from radiation by ensuring that such wastes are appropriately managed, while simultaneously reducing the current level of dual regulation. In terms of health protection, dual regulation of very small quantities of radionuclides provides no benefit.

In this paper, the influence of measurement errors in exposure doses in a regression model with binary response is studied. Recently, it has been recognized that uncertainty in exposure dose is characterized by errors of two types: classical additive errors and Berkson multiplicative errors. The combination of classical additive and Berkson multiplicative errors has not been considered in the literature previously. In a simulation study based on data from radio-epidemiological research of thyroid cancer in Ukraine caused by the Chornobyl accident, it is shown that ignoring measurement errors in doses leads to overestimation of background prevalence and underestimation of excess relative risk. In the work, several methods to reduce these biases are proposed. They are new regression calibration, an additive version of efficient SIMEX, and novel corrected score methods. PMID:26795191

Current models to estimateradiation risk use the Life Span Study (LSS) cohort that received high doses and high dose rates of radiation. Transferring risks from these high dose rates to the low doses and dose rates received by astronauts in space is a source of uncertainty in our risk calculations. The solid cancer models recommended by BEIR VII [1], UNSCEAR [2], and Preston et al [3] is fitted adequately by a linear dose response model, which implies that low doses and dose rates would be estimated the same as high doses and dose rates. However animal and cell experiments imply there should be curvature in the dose response curve for tumor induction. Furthermore animal experiments that directly compare acute to chronic exposures show lower increases in tumor induction than acute exposures. A dose and dose rate effectiveness factor (DDREF) has been estimated and applied to transfer risks from the high doses and dose rates of the LSS cohort to low doses and dose rates such as from missions in space. The BEIR VII committee [1] combined DDREF estimates using the LSS cohort and animal experiments using Bayesian methods for their recommendation for a DDREF value of 1.5 with uncertainty. We reexamined the animal data considered by BEIR VII and included more animal data and human chromosome aberration data to improve the estimate for DDREF. Several experiments chosen by BEIR VII were deemed inappropriate for application to human risk models of solid cancer risk. Animal tumor experiments performed by Ullrich et al [4], Alpen et al [5], and Grahn et al [6] were analyzed to estimate the DDREF. Human chromosome aberration experiments performed on a sample of astronauts within NASA were also available to estimate the DDREF. The LSS cohort results reported by BEIR VII were combined with the new radiobiology results using Bayesian methods.

In order to assess the level of residual radioactivity and evaluate the radiological conditions at the former French nuclear testing sites of Reggane and Taourirt Tan Afella in the south of Algeria, the International Atomic Energy Agency, at the request of the government of Algeria, conducted a field mission to the sites in 1999. At these locations, France conducted a number of nuclear tests in the early 1960s. At the ground zero locality of the ''Gerboise Blanche'' atmospheric test (Reggane) and in the vicinity of a tunnel where radioactive lava was ejected during a poorly contained explosion (Taourirt Tan Afella), non-negligible levels of radioactive material could still be measured. Using the information collected and using realistic potential exposure scenarios, radiationdoses to potential occupants and visitors to the sites were estimated. PMID:18513985

Specific absorbed fractions (SAFs) have been calculated as a function of the content in the urinary bladder in order to allow more realistic calculations of the absorbed dose to the bladder wall. The SAFs were calculated using the urinary bladder anatomy from the ICRP male and female adult reference computational phantoms. The urinary bladder and its content were approximated by a sphere with a wall of constant mass, where the thickness of the wall depended on the amount of urine in the bladder. SAFs were calculated for males and females with 17 different urinary bladder volumes from 10 to 800 mL, using the Monte Carlo computer program MCNP5, at 25 energies of mono-energetic photons and electrons ranging from 10 KeV to 10 MeV. The decay was assumed to be homogeneously distributed in the urinary bladder content and the urinary bladder wall, and the mean absorbed dose to the urinary bladder wall was calculated. The Monte Carlo simulations were validated against measurements made with thermoluminescent dosimeters. The SAFs obtained for a urine volume of 200 mL were compared to the values calculated for the urinary bladder wall using the adult reference computational phantoms. The mean absorbed dose to the urinary wall from 18F-FDG was found to be 77 µGy/MBq formales and 86 µGy/MBq for females, while for 99mTc-DTPA the mean absorbed doses were 80 µGy/MBq for males and 86 µGy/MBq for females. Compared to calculations using a constant value of the SAF from the adult reference computational phantoms, the mean absorbed doses to the bladder wall were 60% higher for 18F-FDG and 30% higher for 99mTc-DTPA using the new SAFs.

Daily dietary intakes of two naturally occurring long-lived radionuclides, 232Th and 238U, were estimated for the adult population living in a number of Asian countries, using highly sensitive analytical methods such as instrumental and radiochemical neutron activation analysis (INAA and RNAA), and inductively coupled plasma mass spectrometry (ICP-MS). The Asian countries that participated in the study were Bangladesh (BGD), China (CPR), India (IND), Japan (JPN), Pakistan (PAK), Philippines (PHI), Republic of Korea (ROK) and Vietnam (VIE). Altogether, these countries represent more than 50% of the world population. The median daily intakes of 232Th ranged between 0.6 and 14.4 mBq, the lowest being for Philippines and the highest for Bangladesh, and daily intakes of 238U ranged between 6.7 and 62.5 mBq, lowest and the highest being for India and China, respectively. The Asian median intakes were obtained as 4.2 mBq for 232Th and 12.7 mBq for 238U. Although the Asian intakes were lower than intakes of 12.3 mBq (3.0 ug) 232Th and 23.6 mBq (1.9 ug) 238U proposed by the International Commission on Radiological Protection (ICRP) for the ICRP Reference Man, they were comparable to the global intake values of 4.6 mBq 232Th and 15.6 mBq 238U proposed by the United Nation Scientific Commission on Effects of Radiation (UNSCEAR). The annual committed effective doses to Asian population from the dietary intake of 232Th and 238U were calculated to be 0.34 and 0.20 microSv, respectively, which are three orders of magnitude lower than the global average annual radiationdose of 2400 microSv to man from the natural radiation sources as proposed by UNSCEAR. PMID:15381318

Different cement samples commonly used in building construction in Turkey have been analyzed for natural radioactivity using gamma-ray spectrometry. The mean activity concentrations observed in the cement samples were 52, 40 and 324 Bq kg(-1) for (226)Ra, (232)Th and (40)K, respectively. The measured activity concentrations for these radionuclides were compared with the reported data of other countries and world average limits. The radiological hazard parameters such as radium equivalent activities (Ra(eq)), gamma index (I(gamma)) and alpha index (I(alpha)) indices as well as terrestrial absorbed dose and annual effective dose rate were calculated and compared with the international data. The Ra(eq) values of cement are lower than the limit of 370 Bq kg(-1), equivalent to a gamma dose of 1.5 mSv y(-1). Moreover, the mass attenuation coefficients were determined experimentally and calculated theoretically using XCOM in some cement samples. Also, chemical compositions analyses of the cement samples were investigated. PMID:20018450

The activity concentration of (226)Ra, (232)Th and (40)K was measured for soil samples collected from 34 locations of Tumkur District, Karnataka, India, using HPGe detector. The activity concentration of (226)Ra, (232)Th and (40)K varied from 9.6 to 71.6, 12.3 to 333.3 and 194.3 to 1527.7 Bq kg(-1) with an average value of 33.15, 123.01 and 877.76 Bq kg(-1), respectively. The absorbed and annual effective outdoor doses were found to be highest at Ponnasamudra with 258.98 nGy h(-1) and 317.62 μSv and lowest at Sira with 36.42 nGy h(-1) and 44.67 μSv, respectively. The external hazard index ranged from 0.21 to 1.58 with an average of 0.75. It was significant in 11 locations as it exceeded unity. PMID:23907323

A Polonium metabolic model was derived and incorporated into a Fortran algorithm which estimates the systemic radiationdose from {sup 210}Po when applied to occupational urine bioassay data. The significance of the dosesestimated are examined by defining the degree of uncertainty attached to them through comprehensive statistical testing procedures. Many parameters necessary for dosimetry calculations (such as organ partition coefficients and excretion fractions), were evaluated from metabolic studies of {sup 210}Po in non-human primates. Two tamarins and six baboons were injected intravenously with {sup 210}Po citrate. Excreta and blood samples were collected. Five of the baboons were sacrificed at times ranging from 1 day to 3 months post exposure. Complete necropsies were performed and all excreta and the majority of all skeletal and tissue samples were analyzed radiochemically for their {sup 210}Po content. The {sup 210}Po excretion rate in the baboon was more rapid than in the tamarin. The biological half-time of {sup 210}Po excretion in the baboon was approximately 15 days while in the tamarin, the {sup 210}Po excretion rate was in close agreement with the 50 day biological half-time predicted by ICRP 30. Excretion fractions of {sup 210}Po in the non-human primates were found to be markedly different from data reported elsewhere in other species, including man. A thorough review of the Po urinalysis procedure showed that significant recovery losses resulted when metabolized {sup 210}Po was deposited out of raw urine. Polonium-210 was found throughout the soft tissues of the baboon but not with the partition coefficients for liver, kidneys, and spleen that are predicted by the ICRP 30 metabolic model. A fractional distribution of 0.29 for liver, 0.07 for kidneys, and 0.006 for spleen was determined. Retention times for {sup 210}Po in tissues are described by single exponential functions with biological half-times ranging from 15 to 50 days.

diagnostic mammography, the median MGD from dedicated breast CT was approximately 13.5% higher than that from diagnostic mammography. The MGD for breast CT is based on a 1.45 mm skin layer and that for diagnostic mammography is based on a 4 mm skin layer; thus, favoring a lower estimate for MGD from diagnostic mammography. The median MGD from dedicated breast CT corresponds to the median MGD from four to five diagnostic mammography views. In comparison, for the same 133 breasts, the mean and the median number of views per breast during diagnostic mammography were 4.53 and 4, respectively. Paired analysis showed that there was approximately equal likelihood of receiving lower MGD from either breast CT or diagnostic mammography. Future work will investigate methods to reduce and optimize radiationdose from dedicated breast CT.

Many studies have been conducted on radiationdoses to residents after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Time spent outdoors is an influential factor for external doseestimation. Since little information was available on actual time spent outdoors for residents, different values of average time spent outdoors per day have been used in doseestimation studies on the FDNPP accident. The most conservative value of 24 h was sometimes used, while 2.4 h was adopted for indoor workers in the UNSCEAR 2013 report. Fukushima Medical University has been estimating individual external doses received by residents as a part of the Fukushima Health Management Survey by collecting information on the records of moves and activities (the Basic Survey) after the accident from each resident. In the present study, these records were analyzed to estimate an average time spent outdoors per day. As an example, in Iitate Village, its arithmetic mean was 2.08 h (95% CI: 1.64-2.51) for a total of 170 persons selected from respondents to the Basic Survey. This is a much smaller value than commonly assumed. When 2.08 h is used for the external doseestimation, the dose is about 25% (23-26% when using the above 95% CI) less compared with the doseestimated for the commonly used value of 8 h. PMID:27034103

Purpose: Radiation-dose awareness and optimization in CT can greatly benefit from a dose-reporting system that provides dose and risk estimates specific to each patient and each CT examination. As the first step toward patient-specific dose and risk estimation, this article aimed to develop a method for accurately assessing radiationdose from CT examinations. Methods: A Monte Carlo program was developed to model a CT system (LightSpeed VCT, GE Healthcare). The geometry of the system, the energy spectra of the x-ray source, the three-dimensional geometry of the bowtie filters, and the trajectories of source motions during axial and helical scans were explicitly modeled. To validate the accuracy of the program, a cylindrical phantom was built to enable dose measurements at seven different radial distances from its central axis. Simulated radial dose distributions in the cylindrical phantom were validated against ion chamber measurements for single axial scans at all combinations of tube potential and bowtie filter settings. The accuracy of the program was further validated using two anthropomorphic phantoms (a pediatric one-year-old phantom and an adult female phantom). Computer models of the two phantoms were created based on their CT data and were voxelized for input into the Monte Carlo program. Simulated dose at various organ locations was compared against measurements made with thermoluminescent dosimetry chips for both single axial and helical scans. Results: For the cylindrical phantom, simulations differed from measurements by -4.8% to 2.2%. For the two anthropomorphic phantoms, the discrepancies between simulations and measurements ranged between (-8.1%, 8.1%) and (-17.2%, 13.0%) for the single axial scans and the helical scans, respectively. Conclusions: The authors developed an accurate Monte Carlo program for assessing radiationdose from CT examinations. When combined with computer models of actual patients, the program can provide accurate dose

This study compares three anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ radiationdose and dose rates from molybdenum-99 ((99)Mo) uptake in the liver and GI tract. Model comparison and refinement is important to the process of determining accurate doses and dose rates to the whole body and the various organs. Accurate and consistent dosimetry is crucial to the determination of appropriate dose-effect relationships for use in environmental risk assessment. The computational phantoms considered are (1) a geometrically defined model employing anatomically relevant organ size and location, (2) voxel reconstruction of internal anatomy obtained from CT imaging, and (3) a new model utilizing NURBS surfaces to refine the model in (2). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling and combined with empirical models for predicting activity concentration to estimatedose rates and ultimately determine cumulative radiationdose (μGy) to selected organs after several half-lives of (99)Mo. The computational models provided similar results, especially for organs that were both the source and target of radiation (less than 30% difference between all models). Values in the empirical model as well as the 14 day cumulative organ doses determined from (99)Mo uptake are compared to similar models developed previously for (131)I. Finally, consideration is given to treating the GI tract as a solid organ compared to partitioning it into gut contents and GI wall, which resulted in an order of magnitude difference in estimateddose for most organs. PMID:26048012

Purpose: Radiation-dose awareness and optimization in CT can greatly benefit from a dose-reporting system that provides dose and risk estimates specific to each patient and each CT examination. As the first step toward patient-specific dose and risk estimation, this article aimed to develop a method for accurately assessing radiationdose from CT examinations. Methods: A Monte Carlo program was developed to model a CT system (LightSpeed VCT, GE Healthcare). The geometry of the system, the energy spectra of the x-ray source, the three-dimensional geometry of the bowtie filters, and the trajectories of source motions during axial and helical scans were explicitly modeled. To validate the accuracy of the program, a cylindrical phantom was built to enable dose measurements at seven different radial distances from its central axis. Simulated radial dose distributions in the cylindrical phantom were validated against ion chamber measurements for single axial scans at all combinations of tube potential and bowtie filter settings. The accuracy of the program was further validated using two anthropomorphic phantoms (a pediatric one-year-old phantom and an adult female phantom). Computer models of the two phantoms were created based on their CT data and were voxelized for input into the Monte Carlo program. Simulated dose at various organ locations was compared against measurements made with thermoluminescent dosimetry chips for both single axial and helical scans. Results: For the cylindrical phantom, simulations differed from measurements by −4.8% to 2.2%. For the two anthropomorphic phantoms, the discrepancies between simulations and measurements ranged between (−8.1%, 8.1%) and (−17.2%, 13.0%) for the single axial scans and the helical scans, respectively. Conclusions: The authors developed an accurate Monte Carlo program for assessing radiationdose from CT examinations. When combined with computer models of actual patients, the program can provide accurate dose

The article presents a new procedure of calculating the shielding functions for irregular objects formed from a set of nonintersecting (adjacent) triangles covering completely the surface of each object. Calculated and experimentally derived distributions of space ionizing radiationdoses in the spherical tissue-equivalent phantom (experiment MATRYOSHKA-R) inside the International space station were in good agreement in the mass of phantom depths with allowance for measurement error (-10%). The procedure can be applied in modeling radiation loads on cosmonauts, calculating effectiveness of secondary protection in spacecraft, and design review of radiation protection for future space exploration missions. PMID:23457971

A series of 22 patients have been studied using a prototype Multiwire Proportional Chamber Positron Camera to determine the accuracy of measurement of thyroid uptake of radioiodine. The patients being treated for thyrotoxicosis were given a solution containing 1.5 mCi of I-131 and 0.7 mCi of I-124. In a few case 0.3 mCi of I-124 was given prior to I-131 therapy. Data acquisition consisted of 8 contiguous views of the thyroid covering the full 360 degrees around the patient. Each study contained approximately 400,000 events. Data analysis consisted of a simple backprojection and 3D deconvolution of the point source response function to produce a 64x64x64 volume matrix using 0.27ml voxels. The volume of the thyroid was obtained using a simple thresholding technique to determine the number of voxels within the thyroid. Phantom measurements show that the functional volume and hence the radiationdose to the thyroid can be estimated to approx. =10%. From conventional imaging with a gamma camera plus pinhole collimator, 18 out of 22 patients were diagnosed as having uniform Graves disease. The high resolution tomographic information provided by PET imaging has shown that the uptake in 5 of these 18 patients was multinodular. In one case the volume of the nodules within the thyroid was estimated to be 45% of the organ volume. This non-uniform uptake of iodine within the thyroid has consequences for the overall management of hyperthyroidism in patients thought to have Graves disease. It may in part explain the cases of unexpected post therapy hypothyroidism.

We have used the MatTek 3-dimensional human skin model to study the gene expression response of a 3D model to low and high dose low LET radiation, and to study the radiation bystander effect as a function of distance from the site of irradiation with either alpha particles or low LET protons. We have found response pathways that appear to be specific for low dose exposures, that could not have been predicted from high dose studies. We also report the time and distance dependent expression of a large number of genes in bystander tissue. the bystander response in 3D tissues showed many similarities to that described previously in 2D cultured cells, but also showed some differences.

The estimates of absorbed doses of x rays and excess risk of cancer in bone marrow and heavily irradiated sites are extremely crude and are based on very limited data and on a number of assumptions. Some of these assumptions may later prove to be incorrect, but it is probable that they are correct to within a factor of 2. The excess cancer risk estimates calculated compare well with the most reliable epidemiological surveys thus far studied. This is particularly important for cancers of heavily irradiated sites with long latent periods. The mean followup period for the patients was 16.2 y, and an increase in cancers of heavily irradiated sites may appear in these patients in the 1970s in tissues and organs with long latent periods for the induction of cancer. The accuracy of these estimates is severely limited by the inadequacy of information on doses absorbed by the tissues at risk in the irradiated patients. The information on absorbed dose is essential for an accurate assessment of dose-cancer incidence analysis. Furthermore, in this valuable series of irradiated patients, the information on radiation dosimetry on the radiotherapy charts is central to any reliable determination of somatic risks of radiation with regard to carcinogenesis in man. The work necessary to obtain these data is under way; only when they are available can more precise estimates of risk of cancer induction by radiation in man be obtained.

Current safety limits for cataract development after acute exposure to ultraviolet radiation (UVR) are based on experiments analyzing experimental data with a quantal, effect-no effect, dose-response model. The present study showed that intensity of forward light scattering is better described with a continuous dose-response model. It was found that 3, 30 and 300 kJ/m2UVR300nm induces increased light scattering within 6 h. For all three doses the intensity of forward light scattering was constant after 6 h. The intensity of forward light scattering was proportional to the log dose of UVR300nm. There was a slight increase of the intensity of forward light scattering on the contralateral side in animals that received 300 kJ/m2. Altogether 72 Sprague-Dawley male rats were included. Half of the rats were exposed in vivo on one side to UVR300nm. The other half was kept as a control group, receiving the same treatment as exposed rats but without delivery of UVR300nm to the eye. Subgroups of the rats received either of the three doses. Rats were sacrificed at varying intervals after the exposure. The lenses were extracted and the forward light scattering was estimated. It is concluded that intensity of forward light scattering in the lens after exposure to UVR300nm should be described with a continuous dose-reponse model.

A Task Group within the ICRP Committees 2 and 3 is continuously working to improve absorbed doseestimates to patients investigated with radiopharmaceuticals. The work deals with reviews of the literature, initiation of new or complementary studies of the biokinetics of a compound and doseestimates. Absorbed dose calculations for organs and tissues have up to now been carried out using the MIRD formalism. There is still a lack of necessary biokinetic data from measurements in humans. More time series obtained by nuclear medicine imaging techniques such as whole-body planar gamma-camera imaging, SPECT or PET are highly desirable for this purpose. In 2008, a new addendum to ICRP Publication 53 was published under the name of ICRP Publication 106 containing biokinetic data and absorbed dose information to organs and tissues of patients of various ages for radiopharmaceuticals in common use. That report also covers a number of generic models and realistic maximum models covering other large groups of substances (e.g. "123I-brain receptor substances"). Together with ICRP Publication 80, most radiopharmaceuticals in clinical use at the time of publication were covered except the radioiodine labeled compounds for which the ICRP doseestimates are still found in Publication 53. There is an increasing use of new radiopharmaceuticals, especially PET-tracers and the TG has recently finished its work with biokinetic and dosimetric data for 18F-FET, 18F-FLT and 18F-choline. The work continues now with new data for 11C-raclopride, 11C-PiB and 123I-ioflupan as well as re-evaluation of published data for 82Rb-chloride, 18F-fluoride and radioiodide. This paper summarises published ICRP-information on dose to patients from radiopharmaceuticals and gives some preliminary data for substances under review.

The objective was to conduct confirmatory research on aerosol characteristics and the resulting radiationdose distribution in animals following inhalation and to provide prediction of health consequences in humans due to airborne radioactivity which might be released in normal operations or under accident conditions during production of nuclear fuel composed of mixed oxides of U and Pu. Four research reports summarize the results of specific areas of research. The first paper details development of a method for determination of specific surface area of small samples of mixed oxide or pure PuO/sub 2/ particles. The second paper details the extension of the biomathematical model previously used to describe retention, distribution and excretion of Pu from these mixed oxide aerosols to include a description of Am and U components of these aerosols. The third paper summarizes the biological responses observed in radiationdose pattern studies in which dogs, monkeys and rate received inhalation exposures to either 750/sup 0/C heat treated UO/sub 2/ + PuO/sub 2/, 1750/sup 0/C heat-treated (U,Pu)O/sub 2/ or 850/sup 0/C heat-treated pure PuO/sub 2/. The fourth paper described dose-response studies in which rats were exposed to (U,Pu)O/sub 2/ or pure PuO/sub 2/. This paper updates earlier reports and summarizes the status of animals through approximately 650 days after inhalation.

Purpose: To compare CT-based volumetric calculations and International Commission on Radiation Units and Measurements (ICRU) reference-point estimates of radiationdoses to the bladder and rectum in patients with carcinoma of the uterine cervix treated with definitive low-dose-rate intracavitary radiotherapy (ICRT). Methods and Materials: Between November 2001 and March 2003, 60 patients were prospectively enrolled in a pilot study of ICRT with CT-based dosimetry. Most patients underwent two ICRT insertions. After insertion of an afterloading ICRT applicator, intraoperative orthogonal films were obtained to ensure proper positioning of the system and to facilitate subsequent planning. Treatments were prescribed using standard two-dimensional dosimetry and planning. Patients also underwent helical CT of the pelvis for three-dimensional reconstruction of the radiationdose distributions. The systems were loaded with {sup 137}Cs sources using the Selectron remote afterloading system according to institutional practice for low-dose-rate brachytherapy. Three-dimensional dose distributions were generated using the Varian BrachyVision treatment planning system. The rectum was contoured from the bottom of the ischial tuberosities to the sigmoid flexure. The entire bladder was contoured. The minimal doses delivered to the 2 cm{sup 3} of bladder and rectum receiving the highest dose (D{sub BV2} and D{sub RV2}, respectively) were determined from dose-volume histograms, and these estimates were compared with two-dimensionally derived estimates of the doses to the corresponding ICRU reference points. Results: A total of 118 unique intracavitary insertions were performed, and 93 were evaluated and the subject of this analysis. For the rectum, the estimateddoses to the ICRU reference point did not differ significantly from the D{sub RV2} (p = 0.561); the mean ({+-} standard deviation) difference was 21 cGy ({+-} 344 cGy). The median volume of the rectum that received at least

Civil airliner passengers and crew are exposed to elevated levels of radiation relative to being at sea level. Previous studies have assessed the radiationdose received in particular cases or for cohort studies. Here we present the first estimate of the total radiationdose received by the worldwide civilian flying population. We simulated flights globally from 2000 to 2013 using schedule data, applying a radiation propagation code to estimate the dose associated with each flight. Passengers flying in Europe and North America exceed the International Commission on Radiological Protection annual dose limits at an annual average of 510 or 420 flight hours per year, respectively. However, this falls to 160 or 120 h on specific routes under maximum exposure conditions. PMID:26769857

In collaboration with the Ukrainian Research Center for Radiation Medicine, the U.S. National Cancer Institute initiated a cohort study of children and adolescents exposed to Chornobyl fallout in Ukraine to better understand the long-term health effects of exposure to radioactive iodines. All 13,204 cohort members were subjected to at least one direct thyroid measurement between 30 April and 30 June 1986 and resided at the time of the accident in the northern part of Kyiv, Zhytomyr, or Chernihiv Oblasts, which were the most contaminated territories of Ukraine as a result of radioactive fallout from the Chornobyl accident. Thyroid doses for the cohort members, which had been estimated following the first round of interviews, were re-evaluated following the second round of interviews. The revised thyroid doses range from 0.35 mGy to 42 Gy, with 95 percent of the doses between 1 mGy and 4.2 Gy, an arithmetic mean of 0.65 Gy, and a geometric mean of 0.19 Gy. These means are 70% of the previous estimates, mainly because of the use of country-specific thyroid masses. Many of the individual thyroid doseestimates show substantial differences because of the use of an improved questionnaire for the second round of interviews. Limitations of the current set of thyroid doseestimates are discussed. For the epidemiologic study, the most notable improvement is a revised assessment of the uncertainties, as shared and unshared uncertainties in the parameter values were considered in the calculation of the 1,000 stochastic estimates of thyroid dose for each cohort member. This procedure makes it possible to perform a more realistic risk analysis. PMID:25208014

The Lawrence Livermore National Laboratory Atmospheric Release Advisory Capability (ARAC) responded to the Chernobyl nuclear reactor accident in the Soviet Union by utilizing long-range atmospheric dispersion modeling to estimate the amount of radioactivity released (source term) and the radiationdose distribution due to exposure to the radioactive cloud over Europe and the Northern Hemisphere. In later assessments, after the release of data on the accident by the Soviet Union, the ARAC team used their mesoscale to regional scale model to focus in on the radiationdose distribution within the Soviet Union and the vicinity of the Chernobyl plant. 22 refs., 5 figs., 5 tabs.

The complexity of radiation environments in space makes estimation of risks more difficult than for the protection of terrestrial populations. In deep space the duration of the mission, position in the solar cycle, number and size of solar particle events (SPE) and the spacecraft shielding are the major determinants of risk. In low-earth orbit missions there are the added factors of altitude and orbital inclination. Different radiation qualities such as protons and heavy ions and secondary radiations inside the spacecraft such as neutrons of various energies, have to be considered. Radiationdose rates in space are low except for short periods during very large SPEs. Risk estimation for space activities is based on the human experience of exposure to gamma rays and to a lesser extent X rays. The doses of protons, heavy ions and neutrons are adjusted to take into account the relative biological effectiveness (RBE) of the different radiation types and thus derive equivalent doses. RBE values and factors to adjust for the effect of dose rate have to be obtained from experimental data. The influence of age and gender on the cancer risk is estimated from the data from atomic bomb survivors. Because of the large number of variables the uncertainities in the probability of the effects are large. Information needed to improve the risk estimates includes: (1) risk of cancer induction by protons, heavy ions and neutrons: (2) influence of dose rate and protraction, particularly on potential tissue effects such as reduced fertility and cataracts: and (3) possible effects of heavy ions on the central nervous system. Risk cannot be eliminated and thus there must be a consensus on what level of risk is acceptable. PMID:12382925

There are more than one thousand residents who lived in about 140 radiation-contaminated buildings and received the assessed radiationdose equivalent over 5 mSv/year. In this paper, a systematic approach to dose reconstruction is proposed for evaluating radiationdose equivalent to the residents. The approach includes area survey and exposure measurement, source identification and energy spectrum analysis, special designed TLD-embedded badges for residents to wear and organ doseestimation with Rando phantom simulation. From the study, it is concluded that the ionization chamber should still be considered as the primary modality for external dose measurement. However, lacking of accurate daily activity patterns of the residents, the dose equivalent estimation with the chamber measurements would be somehow overestimated. The encountered limitation could be compensated with the use of the TLD badges and Rando phantom simulation that could also provide more information for internal organ dose equivalent estimations. As the radiation patterns in the buildings are highly anisotropic, which strongly depends on the differences of structural and indoor layouts, it demands a mathematical model dealing with the above concerns. Also, further collaborations with studies on biological markers of the residents would make the entire dose equivalent estimation more helpful and reliable.

The measurement of ionization distribution caused by the cosmic ray ionizing components in the air, the survey of population distribution in geography and the investigation of total passengers taking air liners at the mainland of China have been completed. By taking the data from the census of the year 1986 and the population distribution of the mainland, considering the cosmic ray distribution with the height and referring the distribution of neutron flux density in cosmic rays, the population-weighted mean annual effective dose equivalent, which is obtained from 2017 counties and 353 cities, for inhabitants living in every provinces and municipalities directly under Central Government has been calculated. The collective dose equivalent produced by the external exposure of cosmic rays is also estimated when people are taking air liners. The results which are effected by the population distribution show that the annual effective dose equivalant received by the population of China from cosmic rays is 28 lower lower than the population of the world. Most of Chinese people are living in the Northern Hemisphere area that has a lower elevation and geomagnetic latitude, and 53.6 percent of them are in the area of elevation below 100 m and 91 percent are in the area of geomagnetic latitude below 30 deg N.

The radiation environment on the Moon includes albedo neutrons produced by primary particles interacting with the lunar surface. In this work, HZETRN2010 is used to calculate the albedo neutron contribution to effective dose as a function of shielding thickness for four different space radiation environments and to determine to what extent various factors affect such estimates. First, albedo neutron spectra computed with HZETRN2010 are compared to Monte Carlo results in various radiation environments. Next, the impact of lunar regolith composition on the albedo neutron spectrum is examined, and the variation on effective dose caused by neutron fluence-to-effective dose conversion coefficients is studied. A methodology for computing effective dose in detailed human phantoms using HZETRN2010 is also discussed and compared. Finally, the combined variation caused by environmental models, shielding materials, shielding thickness, regolith composition and conversion coefficients on the albedo neutron contribution to effective dose is determined. It is shown that a single percentage number for characterizing the albedo neutron contribution to effective dose can be misleading. In general, the albedo neutron contribution to effective dose is found to vary between 1-32%, with the environmental model, shielding material and shielding thickness being the driving factors that determine the exact contribution. It is also shown that polyethylene or other hydrogen-rich materials may be used to mitigate the albedo neutron exposure. PMID:21859325

Following cancer radiotherapy, reconstruction of doses to organs, other than the target organ, is of interest for retrospective health risk studies. Reliable estimation of doses to organs that may be partially within or fully outside the treatment field requires reliable knowledge of the location and size of the organs, e.g., the stomach, which is at risk from abdominal irradiation. The stomach location and size are known to be highly variable between individuals, but have been little studied. Moreover, for treatments conducted years ago, medical images of patients are usually not available in medical records to locate the stomach. In light of the poor information available to locate the stomach in historical dose reconstructions, the purpose of this work was to investigate the variability of stomach location and size among adult male patients and to develop prediction models for the stomach location and size using predictor variables generally available in medical records of radiotherapy patients treated in the past. To collect data on stomach size and position, we segmented the contours of the stomach and of the skeleton on contemporary computed tomography (CT) images for 30 male patients in supine position. The location and size of the stomach was found to depend on body mass index (BMI), ponderal index (PI), and age. For example, the anteroposterior dimension of the stomach was found to increase with increasing BMI (≈0.25 cm kg-1 m2) whereas its craniocaudal dimension decreased with increasing PI (≈-3.3 cm kg-1 m3) and its transverse dimension increased with increasing PI (≈2.5 cm kg-1 m3). Using the prediction models, we generated three-dimensional computational stomach models from a deformable hybrid phantom for three patients of different BMI. Based on a typical radiotherapy treatment, we simulated radiotherapy treatments on the predicted stomach models and on the CT images of the corresponding patients. Those dose calculations demonstrated good

This global map of Mars shows the estimatedradiation dosages from cosmic rays reaching the surface, a serious health concern for any future human exploration of the planet.

The estimates are based on cosmic-radiation measurements by the Mars radiation environment experiment, an instrument on NASA's Mars 2000 Odyssey spacecraft, plus information about Mars' surface elevations from the laser altimeter instrument on NASA's Mars Global Surveyor. The areas of Mars expected to have the lowest levels of cosmic radiation are where the elevation is lowest, because those areas have more atmosphere above them to block out some of the radiation. Earth's thick atmosphere shields us from most cosmic radiation, but Mars has a much thinner atmosphere than we have on Earth.

The colors in the map refer to the estimated annual dose equivalent in rems, a unit of radiationdose. The range is generally from 10 rems(color-coded dark blue) to 20 rems (color coded dark red). Radiation exposure for astronauts on the International Space Station in Earth orbit is typically equivalent to an annualized rate of 20 to 40 rems.

NASA's Jet Propulsion Laboratory, Pasadena, Calif. manages the 2001 Mars Odyssey and Mars Global Surveyor missions for NASA's Office of Space Science, Washington D.C. The Mars radiation environment experiment was developed by NASA's Johnson Space Center, Houston. Lockheed Martin Astronautics, Denver, is the prime contractor for Odyssey, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Few scientific issues arouse as much public controversy as the effects of radiation. This booklet is an attempt to summarize what is known about radiation and provide a basis for further discussion and debate. The first four chapters of the booklet are based on the most recent reports to the United Nations' General Assembly by the United Nations…

The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimateddose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h(-1) (1.2 mGy d(-1)), even 3 years after

The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiationdose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and voxelized patient data. To accomplish this we have modified a general purpose Monte Carlo transport code (MCNP4B) to simulate the CT x-ray source and movement, and then to calculate absorbed radiationdose in desired objects. The movement of the source in either axial or spiral modes was modelled explicitly while the CT system components were modelled using published information about x-ray spectra as well as information provided by the manufacturer. Simulations were performed for single axial scans using the head and body computed tomography dose index (CTDI) polymethylmethacrylate phantoms at both central and peripheral positions for all available beam energies and slice thicknesses. For comparison, corresponding physical measurements of CTDI in phantom were made with an ion chamber. To obtain absolute dose values, simulations and measurements were performed in air at the scanner isocentre for each beam energy. To extend the verification, the CT scanner model was applied to the MIRD V model and compared with published results using similar technical factors. After verification of the model, the generalized source was simulated and applied to voxelized models of patient anatomy. The simulated and measured absolute dose data in phantom agreed to within 2% for the head phantom and within 4% for the body phantom at 120 and 140 kVp; this extends to 8% for the head and 9% for the body phantom across all available beam energies and positions. For the head phantom, the simulated and measured absolute dose data agree to within 2% across all slice thicknesses at 120 kVp. Our results in the MIRD phantom agree within 11% of all the different organ dose values

A combined dose rate meter and charger unit therefor which does not require the use of batteries but on the other hand produces a charging potential by means of a piezoelectric cylinder which is struck by a manually triggered hammer mechanism. A tubular type electrometer is mounted in a portable housing which additionally includes a geiger-muller (Gm) counter tube and electronic circuitry coupled to the electrometer for providing multi-mode operation. In one mode of operation, an rc circuit of predetermined time constant is connected to a storage capacitor which serves as a timed power source for the gm tube, providing a measurement in terms of dose rate which is indicated by the electrometer. In another mode, the electrometer indicates individual counts.

This paper summarizes information about external and internal doses resulting from global fallout and presents preliminary estimates of doses resulting from intermediate fallout in the contiguous United States. Most of the data on global fallout were extracted from the reports of the United Nations Scientific Committee on the Effects of Atomic Radiation, in which the radiation exposures from fallout have been extensively reviewed at regular intervals. United Nations Scientific Committee on the Effects of Atomic Radiationestimated the average effective doses received by the world's population before 2000 to be about 0.4 mSv from external irradiation and 0.6 mSv from internal irradiation, the main radionuclide contributing to the effective dose being 137Cs. Effective doses received beyond 2000 result mainly from the environmentally mobile, long-lived 14C and amount to about 2.5 mSv summed over present and future generations. Specific information about the doses from fallout received by the United States population is based on the preliminary results of a study requested by the U.S. Congress and conducted jointly by the Centers for Disease Control and Prevention and the National Cancer Institute. Separate calculations were made for the tests conducted at the Nevada Test Site and for the high-yield tests conducted mainly by the United States and the former Soviet Union at sites far away from the contiguous United States (global tests). The estimated average doses from external irradiation received by the United States population were about 0.5 mGy for Nevada Test Site fallout and about 0.7 mGy for global fallout. These values vary little from one organ or tissue of the body to another. In contrast, the average doses from internal irradiation vary markedly from one organ or tissue to another; estimated average thyroid doses to children born in 1951 were about 30 mGy from Nevada Test Site fallout and about 2 mGy from global fallout. PMID:12003019

Cancer risk models and their relationship to ionizing radiation are discussed. There are many model assumptions and risk factors that have a large quantitative impact on the cancer risk estimates. Other health end points such as mental retardation may be an even more serious risk than cancer for those with in utero exposures. 8 references.

Objective To compare the probe detection method with the image quantification method when estimating 131I biokinetics and radiationdoses to the red marrow and whole body in the treatment of thyroid cancer patients. Materials and Methods Fourteen patients with metastatic thyroid cancer, without metastatic bone involvement, were submitted to therapy planning in order to tailor the therapeutic amount of 131I to each individual. Whole-body scans and probe measurements were performed at 4, 24, 48, 72, and 96 h after 131I administration in order to estimate the effective half-life (Teff) and residence time of 131I in the body. Results The mean values for Teff and residence time, respectively, were 19 ± 9 h and 28 ± 12 h for probe detection, compared with 20 ± 13 h and 29 ± 18 h for image quantification. The average dose to the red marrow and whole body, respectively, was 0.061 ± 0.041 mGy/MBq and 0.073 ± 0.040 mGy/MBq for probe detection, compared with 0.066 ± 0.055 mGy/MBq and 0.078 ± 0.056 mGy/MBq for image quantification. Statistical analysis proved that there were no significant differences between the two methods for estimating the Teff (p = 0.801), residence time (p = 0.801), dose to the red marrow (p = 0.708), and dose to the whole body (p = 0.811), even when we considered an optimized approach for calculating doses only at 4 h and 96 h after 131I administration (p > 0.914). Conclusion There is full agreement as to the feasibility of using probe detection and image quantification when estimating 131I biokinetics and red-marrow/whole-body doses. However, because the probe detection method is inefficacious in identifying tumor sites and critical organs during radionuclide therapy and therefore liable to skew adjustment of the amount of 131I to be administered to patients under such therapy, it should be used with caution. PMID:27403014

Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Space Environment Technologies (SET) has been conducting space weather observations of the atmospheric radiation environment at aviation altitudes that will eventually be transitioned into air traffic management operations. The Automated Radiation Measurements for Aerospace Safety (ARMAS) system and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) both are providing dose rate measurements. Both activities are under the ARMAS goal of providing the "weather" of the radiation environment to improve aircraft crew and passenger safety. Over 5-dozen ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the real-time radiation environment resulting from Galactic Cosmic Rays and Solar Energetic Particles. The real-time radiation exposure is computed as an effective dose rate (body-averaged over the radiative-sensitive organs and tissues in units of microsieverts per hour); total ionizing dose is captured on the aircraft, downlinked in real-time, processed on the ground into effective dose rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users via the web and smart phone apps. Flight altitudes now exceed 60,000 ft. and extend above commercial aviation altitudes into the stratosphere. In this presentation we describe recent ARMAS and USEWX results.

The characterization and the study of the radiations on their interaction with organic matter is of great interest in view of the human exploration on Mars. The Ionizing RAdiation Sensor (IRAS) selected in the frame of the ExoMars/Pasteur ESA mission is a lightweight particle spectrometer combining various techniques of radiation detection in space. It characterizes the first time the radiation environment on the Mars surface, and provide dose and dose equivalent rates as precursor information absolutely necessary to develop ways to mitigate the radiation risks for future human exploration on Mars. The Martian radiation levels are much higher than those found on Earth and they are relatively low for space. Measurements on the surface will show if they are similar or not to those seen in orbit (modified by the presence of ``albedo'' neutrons produced in the regolith and by the thin Martian atmosphere). IRAS consists of a telescope based on segmented silicon detectors of about 40\\userk\\milli\\metre\\user;k diameter and 300\\user;k\\micro\\metre\\user;k thickness, a segmented organic scintillator, and of a thermoluminescence dosimeter. The telescope will continuously monitor temporal variation of the particle count rate, the dose rate, particle and LET (Linear Energy Transfer) spectra. Tissue equivalent BC430 scintillator material will be used to measure the neutron dose. Neutrons are selected by a criteria requiring no signal in the anti-coincidence. Last, the passive thermoluminescence dosimeter, based on LiF:Mg detectors, regardless the on board operation timing, will measure the total dose accumulated during the exposure period and due to beta and gamma radiation, with a responsivity very close to that of a human tissue.

Using the all solid cancer mortality data set of the Life Span Study (LSS) cohort from 1950 to 2003 (LSS Report 14) data among atomic bomb survivors, excess relative risk (ERR) statistical analyses were performed using the second degree polynomial and the threshold and restricted cubic spline (RCS) dose response models. For the RCS models with 3 to 7 knots of equally spaced percentiles with margins in the dose range greater than 50 mGy, the dose response was assumed to be linear at less than 70 to 90 mGy. Due to the skewed dose distribution of atomic bomb survivors, the current knot system for the RCS analysis results in a detailed depiction of the dose response as less than approximately 0.5 Gy. The 6 knot RCS models for the all-solid cancer mortality dose response of the whole dose or less than 2 Gy were selected with the AIC model selection criterion and fit significantly better (p < 0.05) than the linear (L) model. The usual RCS includes the L-global model but not the quadratic (Q) nor linear-quadratic (LQ) global models. The authors extended the RCS to include L or LQ global models by putting L or LQ constraints on the cubic spline in the lower and upper tails, and the best RCS model selected with AIC criterion was the usual RCS with L-constraints in both the lower and upper tails. The selected RCS had a linear dose-response model in the lower dose range (i.e., < 0.2-0.3 Gy) and was compatible with the linear no-threshold (LNT) model in this dose range. The proposed method is also useful in describing the dose response of a specific cancer or non-cancer disease incidence/mortality. PMID:26011495

In 1951 and 1952 specialists from the Mayak production association investigated the radiological situation in the area of the Metlinski reservoir that was located 5-7 km from the site of liquid radioactive waste (LRW) discharge. Based on their measurements of both the specific radioactivity in the water and the dose-rate above the water surface, the gamma-field above the water surface in 1951 was demonstrated to be mainly due to (95)Zr+(95)Nb. The dose-rate at the shore of the reservoir was calculated for the period 1949-1951. In November and December 1951, the gamma-field at the shore was mainly due to (140)Ba+(140)La. For the period 1949-1951, the external exposure of the Metlino population due to the decay of these radionuclides was about 200 R (2 Sv), most of the dose having been produced in 1951. The contribution of (137)Cs to external doses did at that time probably not exceed a fraction of several percent. This finding is in contradiction to the assumptions made in the most recent TRDS-2000 system that was developed to reconstruct the doses to the residents of the Techa river. The results presented here demonstrate that the reconstruction of external doses received by the Metlino population as well as by the Techa river residents can be improved for the most critical period between 1949 and 1954. PMID:15221313

Recent surveys show that the collective population radiationdose from medical procedures in the U.S. has increased by 750% in the past two decades. It would be impossible to imagine the practice of medicine today without diagnostic and therapeutic radiology, but nevertheless the widespread and rapidly increasing use of a modality which is a known human carcinogen is a cause for concern. To assess the magnitude of the problem it is necessary to establish the shape of the dose response relationship for radiation carcinogenesis. Information on radiation carcinogenesis comes from the A-bomb survivors, from occupationally exposed individuals and from radiotherapy patients. The A-bomb survivor data indicates a linear relationship between dose and the risk of solid cancers up to a dose of about 2.5 Sv. The lowest dose at which there is a significant excess cancer risk is debatable, but it would appear to be between 40 and 100 mSv. Data from the occupation exposure of nuclear workers shows an excess cancer risk at an average dose of 19.4 mSv. At the other end of the dose scale, data on second cancers in radiotherapy patients indicates that cancer risk does not continue to rise as a linear function of dose, but tends towards a plateau of 40 to 60 Gy, delivered in a fractionated regime. These data can be used to estimate the impact of diagnostic radiology at the low dose end of the dose response relationship, and the impact of new radiotherapy modalities at the high end of the dose response relationship. In the case of diagnostic radiology about 90% of the collective population dose comes from procedures (principally CT scans) which involve doses at which there is credible evidence of an excess cancer incidence. While the risk to the individual is small and justified in a symptomatic patient, the same is not true of some screening procedures is asymptomatic individuals, and in any case the huge number of procedures must add up to a potential public health problem. In the

ACRA-TRIT is an atmospheric dispersion code which, using a three- (or two-) dimensional normal distribution model calculates the external dose, the internal dose due to inhalation, and the ground contamination that can be expected from the transport, fallout, and washout of the radioactive products released to the atmosphere in either a continuous fashion or an accidental short-term release. Allowance is made for elevated receptors above ground, for variable height of the plume centerline, and formore » reflection on the ground and on a possible inversion layer in the atmosphere.« less

The size of the thyroid glands was analyzed for 10% of the patients in a selected group that had been exposed to diagnostic doses of /sup 131/I. The mean thyroid gland weight +- SD was 50 +- 33 g for patients 20 or more years of age and 10 +- 5 g for patients less than 20 years of age. With the present follow-up, diagnostic doses of /sup 131/I appeared not to be associated with an increased risk for later development of malignant thyroid tumors. Possible reasons for the difference between the observed number of such tumors and the number expected (47 to 124) on the basis of risk estimates of the United Nations Scientific Committee on the Effects of Atomic Radiation are discussed.

A dedicated X-ray mammography was introduced to our hospital from 1987 and an imaging receptor of xeroradiography was applied. We reported previously that the average air exposure was 0.79R and that the absorption dose of skin was 1.00 rad. These data are similar to literature reports. Screen-film mammography was introduced recently. To select the best breast imaging and the least radiation exposure, diverse methods were investigated. A dosimetry (Capintec model 192) and a PS-033 parallel ionization chamber were applied to compare the absorption dose on polystyrene phantom between various exposure factors, the application of breast clamp and the size of exposure field. Retrospective estimation of the radiationdose was obtained from the exposure factors of previous mammography since July, 1990 to May, 1992. There were 1035 xeromammographic examinations and 358 examinations with medium-speed screen-film mammography. Another 61 craniocaudal and 96 mediolateral projections with high-speed screen-film mammography were recruited during the recent two months. An ionization chamber (Exradin, Shonka-Wyckoff A5) with an electrometer (Keithley 617) wer selected to obtain the dose equivalent from air exposure between selected exposure factors. The radiationdose of mammography is linearly correlated with voltage/kV and current/mAs. The application of a breast clump reduces 10% of the skin dose. The average exposure factors of xeromammography are 45.6 kV, 163.5 mAs. These results remain the same as in our previous report. Xeromammography has a greater exposure to air, estimated average glandular dose and absorbed dose than screen-film mammography. The mean exposure factor of rapid screen-film mammography gains half the value of medium screen-film mammography, ie. 26.6 kV, 87.0 mAs vs. 26.0 kV, 164.5 mAs.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8490794

Since 1946 a continuous effort to evaluate the potential genetic effects of the atomic bombs has been sustained. Observations on children born in Hiroshima and Nagasaki include sex ratio, congenital malformations, stillbirths, survival of liveborn infants, chromosomal abnormalities (sex chromosomal abnormalities and balanced chromosomal rearrangements), mutations altering protein structure or activity, and physical growth and development. There are no statistically significant differences between the children of parents who received increased amounts of radiation at the time of the bombings and those whose parents did not. However, the difference between the two sets of children is consistent with the hypothesis of a genetic effect of the exposure, but its magnitude suggests humans are not as sensitive to the genetic effects of radiation as projected from the mouse paradigm. PMID:2698842

measurement. The amount of {sup 137}Cs detected is often reported in activity units of kilo-Becquerel (kBq), where 1 kBq equals 1000 Bq and 1 Bq = 1 nuclear transformation per second (t s{sup -1}). [However, in the United States the Curie (Ci) continues to be used as the unit of radioactivity; where 1 Ci = 3.7 x 10{sup 10} Bq.] The detection of {sup 239}Pu and {sup 240}Pu in bioassay (urine) samples indicates the presence of internally deposited (systemic) plutonium in the body. Urine samples that are collected in the Marshall Islands from volunteers participating in the RSMP are transported to LLNL, where measurements for {sup 239+240}Pu are performed using a state-of-the-art technology based on Accelerator Mass Spectrometry (AMS) (Hamilton et al., 2004, 2007; Brown et al., 2004). The urinary excretion of plutonium by RSMP volunteers is usually described in activity units, expressed as micro-Becquerel ({micro}Bq) of {sup 239+240}Pu (i.e., representing the sum of the {sup 239}Pu and {sup 240}Pu activity) excreted (lost) per day (d{sup -1}), where 1 {micro}Bq d{sup -1} = 10{sup -6} Bq d{sup -1} and 1 Bq = 1 t s{sup -1}. The systemic burden of plutonium is then estimated from biokinetic relationships as described by the International Commission on Radiological Protection (e.g., see ICRP, 1990). In general, nuclear transformations are accompanied by the emission of energy and/or particles in the form of gamma rays ({gamma}), beta particles ({beta}), and/or alpha particles ({alpha}). Tissues in the human body may adsorb these emissions, where there is a potential for any deposited energy to cause biological damage. The general term used to quantify the extent of any radiation exposure is referred to as the dose. The equivalent dose is defined by the average absorbed dose in an organ or tissue weighted by the average quality factor for the type and energy of the emission causing the dose. The effective dose equivalent (EDE; as applied to the whole body), is the sum of the average

Estimates of radiationdose to the public must be made at each stage in the identification and qualification process leading to siting a high-level nuclear waste repository. Specifically considering the ingestion pathway, this paper examines questions of reliability and adequacy of dose calculations in relation to five stages of data availability (geologic province, region, area, location, and mass balance) and three methods of calculation (population, population/food production, and food production driven). Calculations were done using the model PABLM with data for the Permian and Palo Duro Basins and the Deaf Smith County area. Extra effort expended in gathering agricultural data at succeeding environmental characterization levels does not appear justified, since doseestimates do not differ greatly; that effort would be better spent determining usage of food types that contribute most to the total dose; and that consumption rate and the air dispersion factor are critical to assessment of radiationdose via the ingestion pathway. 17 refs., 9 figs., 32 tabs.

The aim of this study was to assess effective doses of a lateral cephalogram radiograph with and without thyroid shield and compare the differences with the radiationdose of a hand-wrist radiograph. Thermoluminescent dosimeters were placed at 19 different sites in the head and neck of a tissue-equivalent human skull (RANDO phantom). Analogue lateral cephalograms with and without thyroid shield (67 kV, 250 mA, 10 mAs) and hand-wrist radiographs (40 kV, 250 mA, 10 mAs) were obtained. The effective doses were calculated using the 2007 International Commission on Radiological Protection recommendations. The effective dose for conventional lateral cephalogram without a thyroid shield was 5.03 microsieverts (µSv). By applying a thyroid shield to the RANDO phantom, a remarkable dose reduction of 1.73 µSv could be achieved. The effective dose of a conventional hand-wrist radiograph was calculated to be 0.16 µSv. Adding the effective dose of the hand-wrist radiograph to the effective dose of the lateral cephalogram with thyroid shield resulted in a cumulative effective dose of 3.46 µSv. Without thyroid shield, the effective dose of a lateral cephalogram was approximately 1.5-fold increased than the cumulative effective dose of a hand-wrist radiograph and a lateral cephalogram with thyroid shield. Thyroid is an organ that is very sensitive to radiation exposure. Its shielding will significantly reduce the effective dose. An additional hand-wrist radiograph, involving no vulnerable tissues, however, causes very little radiation risk. In accordance with the ALARA (As Low As Reasonably Achievable) principle, if an evaluation of skeletal age is indicated, an additional hand-wrist radiograph seems much more justifiable than removing the thyroid shield. PMID:22828078

OBJECTIVE The introduction of MDCT has increased the utilization of CT in pediatric radiology along with concerns for radiation sequelae. This article reviews general principles of lowering radiationdose, the basic physics that impact radiationdose, and specific CT integrated dose-reduction tools focused on the pediatric population. CONCLUSION The goal of this article is to provide a comprehensive review of the recent literature regarding CT dose reduction methods, their limitations, and an outlook on future developments with a focus on the pediatric population. The discussion will initially focus on general considerations that lead to radiationdose reduction, followed by specific technical features that influence the radiationdose. PMID:23617474

Early treatment of victims of high level acute whole-body x-ray or gamma exposure has been shown to improve their likelihood of survival. However, in such cases, both the magnitude of the exposure and the dosimetry profile(s) of the victim(s) are often not known in detail for days to weeks. A simple dose-prediction algorithm based on lymphocyte kinetics as documented in prior radiation accidents is presented here. This algorithm provides an estimate of dose within the first 8 h following an acute whole-body exposure. Early lymphocyte depletion kinetics after a severe radiation accident follow a single exponential, L(t) = L{sub o}e{sup -k(D)t}, where k(D) is a rate constant, dependent primarily on the average dose, D. Within the first 8 h post-accident, K(D) may be calculated utilizing serial lymphocyte counts. Data from the REAC/TS Radiation Accident Registry were used to develop a dose-prediction algorithm from 43 gamma exposure cases where both lymphocyte kinetics and dose reconstruction were felt to be reasonably reliable. The inverse relationship D(K) may be molded by a simple two parameter curve of the form D = a/(1 + b/K) in the range 0 {le} D {le} 15 Gy, with fitting parameters (mean {+-} SD): a = 13.6 {+-} 1.7 Gy, and b = 1.0 {+-} 0.20 d{sup -1}. Doseestimated in this manner is intended to serve only as a first approximation to guide initial medical management. 31 refs., 4 figs., 2 tabs.

The objective of this study was to investigate the dose enhancement to soft tissue due to backscatter radiation near metal interfaces during head and neck radiotherapy. The influence of titanium-mandibular plate with the screws on radiationdose was tested on four real bones from mandible with the metal and screws fixed. Radiochromic films were used for dosimetry. The bone and metal were inserted through the film at the center symmetrically. This was then placed in a small jig (7 cm × 7 cm × 10 cm) to hold the film vertically straight. The polymer granules (tissue-equivalent) were placed around the film for homogeneous scatter medium. The film was irradiated with 6 MV X-rays for 200 monitor units in Trilogy linear accelerator for 10 cm × 10 cm field size with source to axis distance of 100 cm at 5 cm. A single film was also irradiated without any bone and metal interface for reference data. The absolute dose and the vertical dose profile were measured from the film. There was 10% dose enhancement due to the backscatter radiation just adjacent to the metal-bone interface for all the materials. The extent of the backscatter effect was up to 4 mm. There is significant higher dose enhancement in the soft tissue/skin due to the backscatter radiation from the metallic components in the treatment region. PMID:24600171

In estimating the crew exposures during an EVA, the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more than 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO.

Although the Japanese atomic bomb study and radiotherapy studies have clearly documented cancer risks from high-doseradiation exposures, radiation risk assessment groups have long recognized that protracted or low exposures to low-linear energy transfer radiations are key radiation protection concerns because these are far more common than high-exposure scenarios. Epidemiologic studies of human populations with low-dose or low dose-rate exposures are one approach to addressing those concerns. A number of large studies of radiation workers (Chernobyl clean-up workers, U.S. and Chinese radiological technologists, and the 15-country worker study) or of persons exposed to environmental radiation at moderate to low levels (residents near Techa River, Semipalatinsk, Chernobyl, or nuclear facilities) have been conducted. A variety of studies of medical radiation exposures (multiple-fluoroscopy, diagnostic (131)I, scatter radiationdoses from radiotherapy, etc.) also are of interest. Key results from these studies are summarized and compared with risk estimates from the Japanese atomic bomb study. Ideally, one would like the low-dose and low dose-rate studies to guide radiation risk estimation regarding the shape of the dose-response curve, DDREF (dose and dose-rate effectiveness factor), and risk at low doses. However, the degree to which low-dose studies can do so is subject to various limitations, especially those pertaining to dosimetric uncertainties and limited statistical power. The identification of individuals who are particularly susceptible to radiation cancer induction also is of high interest in terms of occupational and medical radiation protection. Several examples of studies of radiation-related cancer susceptibility are discussed, but none thus far have clearly identified radiation-susceptible genotypes. PMID:19820457

Intravenous urography (IVU) and CT urography (CTU) are efficient radiological examinations for the evaluation of the urinary system disorders. However patients are exposed to a significant radiationdose. The objectives of this study are to: (i) measure and compare patient radiationdose by computed tomography urography (CTU) and conventional intravenous urography (IVU) and (ii) evaluate organ equivalent dose and cancer risks from CTU and IVU imaging procedures. A total of 141 patients were investigated. A calibrated CT machine (Siemens-Somatom Emotion duo) was used for CTU, while a Shimadzu X ray machine was used for IVU. Thermoluminescence dosimeters (TLD-GR200A) were used to measure patients' entrance surface doses (ESD). TLDs were calibrated under reproducible reference conditions. Patients radiationdose values (DLP) for CTU were 172±61 mGy cm, CTDIvol 4.75±2 mGy and effective dose 2.58±1 mSv. Patient cancer probabilities were estimated to be 1.4 per million per CTU examination. Patients ESDs values for IVU were 21.62±5 mGy, effective dose 1.79±1 mSv. CT involves a higher effective dose than IVU. In this study the radiationdose is considered low compared to previous studies. The effective dose from CTU procedures was 30% higher compared to IVU procedures. Wide dose variation between patient doses suggests that optimization is not fulfilled yet.

In vitro dose-response curves are used to describe the relation between chromosome aberrations and radiationdose for human lymphocytes. The lymphocytes are exposed to low-LET radiation, and the resulting dicentric chromosome aberrations follow the Poisson distribution. The expected yield depends on both the magnitude and the temporal distribution of the dose. A general dose-response model that describes this relation has been presented by Kellerer and Rossi (1972, Current Topics on Radiation Research Quarterly 8, 85-158; 1978, Radiation Research 75, 471-488) using the theory of dual radiation action. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting dose-time-response models are intrinsically nonlinear in the parameters. A general-purpose maximum likelihood estimation procedure is described, and estimation for the nonlinear models is illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure.

The current design philosophy of a Mars orbiting vehicle, takeoff and landing systems and the transport return vehicle was taken into consideration for calculating the equivalent doses imparted to cosmonaut's organs and tissues by galactic cosmic rays, solar rays and the Earth's radiation belts, values of the total radiation risk over the lifespan following the mission and over the whole career period, and possible shortening of life expectancy. There are a number of uncertainties that should be evaluated, and radiation limits specified before setting off to Mars. PMID:20803991

Ultraviolet radiation (UVR) has been an effective treatment for a number of chronic skin disorders, and its ability to alleviate these conditions has been well documented. Although nonionizing, exposure to ultraviolet (UV) radiation is still damaging to deoxyribonucleic acid integrity, and has a number of unpleasant side effects ranging from erythema (sunburn) to carcinogenesis. As the conditions treated with this therapy tend to be chronic, exposures are repeated and can be high, increasing the lifetime probability of an adverse event or mutagenic effect. Despite the potential detrimental effects, quantitative ultraviolet dosimetry for phototherapy is an underdeveloped area and better dosimetry would allow clinicians to maximize biological effect whilst minimizing the repercussions of overexposure. This review gives a history and insight into the current state of UVR phototherapy, including an overview of biological effects of UVR, a discussion of UVR production, illness treated by this modality, cabin design and the clinical implementation of phototherapy, as well as clinical doseestimation techniques. Several dose models for ultraviolet phototherapy are also examined, and the need for an accurate computational doseestimation method in ultraviolet phototherapy is discussed.

Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiationdoses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

Described is the Liulin-5 experiment and instrumentation, developed for investigation of the space radiationdoses depth distribution in a human phantom on the Russian Segment of the International Space Station (ISS). Liulin-5 experiment is a part of the international project MATROSHKA-R on ISS. The experiment MATROSHKA-R is aimed to study the depth dose distribution at the sites of critical organs of the human body, using models of human body-anthropomorphic and spherical tissue-equivalent phantoms. The aim of Liulin-5 experiment is long term (4-5 years) investigation of the radiation environment dynamics inside the spherical tissue-equivalent phantom, mounted in different places of the Russian Segment of ISS. Energy deposition spectra, linear energy transfer spectra, flux and dose rates for protons and the biologically-relevant heavy ion components of the galactic cosmic radiation will be measured simultaneously with near real time resolution at different depths of the phantom by a telescope of silicon detectors. Data obtained together with data from other active and passive dosimeters will be used to estimate the radiation risk to the crewmembers, verify the models of radiation environment in low Earth orbit, validate body transport model and correlate organ level dose to skin dose. Presented are the test results of the prototype unit. The spherical phantom will be flown on the ISS in 2004 year and Liulin-5 experiment is planned for 2005 year. PMID:15880917

The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as 226Ra and 210Pb of the uranium series and 228Ra of the thorium series and/or man-made produced radionuclides, such as 137Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for 226Ra varied from 42.5 to 178.6 μSv y-1 (average 79.7 μSv y-1), while for 228Ra from 19.3 to 116.0 μSv y-1 (average 67.1 μSv y-1) and for 210Pb from 47.0 to 134.9 μSv y-1 (average 104.7 μSv y-1), that is the same order of magnitude for each radionuclide. The sum of the effective dose of the three natural radionuclides varied from 151.9 to 401.3 μSv y-1 (average 251.5 μSv y-1). The annual effective dose from 137Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y-1 (average 199.3 nSv y-1).

The radioactivity in tobacco leaves collected from 15 different regions of Greece before cigarette production was studied in order to estimate the effective dose from cigarette tobacco due to the naturally occurring primordial radionuclides, such as {sup 226}Ra and {sup 210}Pb of the uranium series and {sup 228}Ra of the thorium series and/or man-made produced radionuclides, such as {sup 137}Cs of Chernobyl origin. Gamma-ray spectrometry was applied using Ge planar and coaxial type detectors of high resolution and high efficiency. It was concluded that the annual effective dose due to inhalation for adults (smokers) for {sup 226}Ra varied from 42.5 to 178.6 {mu}Sv y{sup -1} (average 79.7 {mu}Sv y{sup -1}), while for {sup 228}Ra from 19.3 to 116.0 {mu}Sv y{sup -1} (average 67.1 {mu}Sv y{sup -1}) and for {sup 210}Pb from 47.0 to 134.9 {mu}Sv y{sup -1} (average 104.7 {mu}Sv y{sup -1}), that is the same order of magnitude for each radionuclide. The sum of the effective dose of the three natural radionuclides varied from 151.9 to 401.3 {mu}Sv y{sup -1} (average 251.5 {mu}Sv y{sup -1}). The annual effective dose from {sup 137}Cs of Chernobyl origin was three orders of magnitude lower as it varied from 70.4 to 410.4 nSv y{sup -1} (average 199.3 nSv y{sup -1})

This research performed simulations using the state-of-art three dimensional computer codes to investigate the interactions of space radiation with materials and quantify the biological dose onboard the International Space Station (ISS) and in a lunar shelter for future manned missions. High-energy space radiation of Trapped Protons, Solar Particle Events, and GCRs particles interactions are simulated using MCNPX and PHITS probabilistic codes. The energy loss and energy deposition within the shielding materials and in a phantom are calculated. The contributions of secondary particles produced by spallation reactions are identified. Recent experimental measurements of absorbed dose in a phantom aboard the International Space Station (ISS) was simulated, and used to determine the most appropriate simulation methodology.

Version 00 SMART calculates radiationdose rate at the center of the outer cask surface. It can be applied to determine the radiationdose rate on each cask if source conditions, characteristic function, and material conditions in the bottle regions are given. MANYCASK calculates radiationdose rate distribution in a space surrounded by many casks. If the dose rate on each cask surface can be measured, MANYCASK can be applied to predict dose spatial dosemore » rate distribution for any case of cask configuration.« less

The increasing prevalence and complexity of fluoroscopically guided interventions (FGI) raises concern regarding radiationdose to patients subjected to the procedure. Despite current evidence showing the risk to patients from the deterministic effects of radiation (e.g. skin burns), radiation induced injuries remain commonplace. This review aims to increase the awareness surrounding radiationdose measurement for patients undergoing FGI. A review of the literature was conducted alongside previous researches from the authors’ department. Studies pertaining to patient dose measurement, its formalism along with current advances and present challenges were reviewed. Current patient monitoring techniques (using available radiation dosimeters), as well as the inadequacy of accepting displayed dose as patient radiationdose is discussed. Furthermore, advances in real-time patient radiationdoseestimation during FGI are considered. Patient dosimetry in FGI, particularly in real time, remains an ongoing challenge. The increasing occurrence and sophistication of these procedures calls for further advances in the field of patient radiationdose monitoring. Improved measuring techniques will aid clinicians in better predicting and managing radiation induced injury following FGI, thus improving patient care.

Prompt and aggressive treatment of victims to high level whole-body gamma exposure has been shown to improve their likelihood of survival. However, in such cases, both the magnitude of the accident and the dosimetry profile(s) of the victim(s) are often not known in detail for days to weeks. Medical intervention could therefore be delayed after a major accident because of uncertainties in the initial doseestimate. A simple dose-prediction algorithm based on lymphocyte kinetics as documented in prior radiation accidents is presented here. This algorithm provides an estimate of marrow dose within the first 12-18 h following an acute whole-body gamma exposure. Early lymphocyte depletion curves post-accident follow a single exponential, L(t) = L{sub o}e{sup -k(D)t}, where L{sub o} is the pre- accident lymphocyte count and k(D) is a rate constant, dependent on the average dose, D. Within the first 12-18 h post-accident, K(D) may be calculated utilizing serial lymphocyte counts. Data from the REAC/TS Accident Registry were used to develop a dose prediction algorithm from 43 gamma exposure cases where both lymphocyte kinetics and dose reconstruction were felt to be reasonably reliable. The relationship D(K) is shown to follow a logistic dose response curve of the form D = a/[1 + (K/b){sup c}] in the range 0 {le} D {le} 15 Gy. The fitting parameters (mean {+-} SD) are found to be a = 21.5 {+-} 5.8 Gy, b = 1.75 {+-} 0.99 d{sup -1}, and c = -0.98 {+-} 0.14, respectively. The coefficient of determination r{sup 2} for the fit is 0.90 with an F-value of 174.7. Doseestimated in this manner is intended to serve only as a first approximation to guide initial medical-management. The treatment regimen may then be modified as needed after more exact dosimetry has become available.

The main principles of the estimation of Radiative danger has been discussed. Two main particularities of the danger were pointed out: negatve consequencies of small doses, which does not lead to radiation sickness, but lead to disfunctions of sanguine organs and thin intestines; absolute estimation of biological anomalies, which was forwarded by A.D. Sakharov (1921-1989). The ethic aspects of the use of Nuclear weapons on the fate of Human civilization were pointed out by A.D. Sakharov (1921-1990).

This seminar will describe development of methods for the estimation of solar radiationdoses in wetlands. The methodology presents a novel approach to incorporating aspects of solar radiation dosimetry that have historically received limited attention. These include effects of a...

Perchlorate is a naturally occurring inorganic anion used as a component of solid rocket fuel, explosives, and pyrotechnics. Sufficiently high perchlorate intakes can modify thyroid function by competitively inhibiting iodide uptake in adults; however, little is known about perchlorate exposure and health effects in infants. Food intake models predict that infants have higher perchlorate exposure doses than adults. For this reason, we measured perchlorate and related anions (nitrate, thiocyanate, and iodide) in 206 urine samples from 92 infants ages 1-377 days and calculated perchlorate intake dose for this sample of infants. The median estimated exposure dose for this sample of infants was 0.160 μg/kg/day. Of the 205 individual doseestimates, 9% exceeded the reference dose of 0.7 μg/kg/day; 6% of infants providing multiple samples had multiple perchlorate doseestimates above the reference dose. Estimated exposure dose differed by feeding method: breast-fed infants had a higher perchlorate exposure dose (geometric mean 0.220 μg/kg/day) than infants consuming cow milk-based formula (geometric mean 0.103 μg/kg/day, p < 0.0001) or soy-based formula (geometric mean 0.027 μg/kg/day, p < 0.0001), consistent with doseestimates based on dietary intake data. The ability of perchlorate to block adequate iodide uptake by the thyroid may have been reduced by the iodine-sufficient status of the infants studied (median urinary iodide 125 μg/L). Further research is needed to see whether these perchlorate intake doses lead to any health effects. PMID:21449579

Perchlorate is a naturally occurring inorganic anion used as a component of solid rocket fuel, explosives, and pyrotechnics. Sufficiently high perchlorate intakes can modify thyroid function by competitively inhibiting iodide uptake in adults; however little is known about perchlorate exposure and health effects in infants. Food intake models predict that infants have higher perchlorate exposure doses than adults. For this reason, we measured perchlorate and related anions (nitrate, thiocyanate, and iodide) in 206 urine samples from 92 infants ages 1–377 days and calculated perchlorate intake dose for this population of infants. The median estimated exposure dose for this population of infants was 0.160 μg/kg/day. Of the 205 individual doseestimates, 9% exceeded the reference dose of 0.7 μg/kg/day; 6% of infants providing multiple samples had multiple perchlorate doseestimates above the reference dose. Estimated exposure dose differed by feeding method: breast-fed infants had a higher perchlorate exposure dose (geometric mean 0.220 μg/kg/day) than infants consuming cow milk-based formula (geometric mean 0.103 μg/kg/day, p<0.0001) or soy-based formula (geometric mean 0.027 μg/kg/day, p<0.0001), consistent with doseestimates based on dietary intake data. The ability of perchlorate to block adequate iodide uptake by the thyroid may have been reduced by the iodine-sufficient status of the infants studied (median urinary iodide 125 μg/L). Further research is needed to see whether these perchlorate intake doses lead to any health effects. PMID:21449579

The treatment for some thyroid carcinomas involves surgically removing the thyroid gland and administering the radiopharmaceutical Sodium iodide-{sup 131}I (NaI). A diagnostic dose of NaI is given to the patient to determine if remnant tissue from the gland remains or larger doses are administered in order to treat the malignant tissue. Past research regarding NaI uptake and retention in euthyroid individuals (normal functioning thyroid) reveal that radioiodine concentrates mainly in the thyroid tissue and the remaining material is excreted from the body. The majority of radioiodine in athyroid (without thyroid) individuals is also eliminated from the body; however, there has been recent evidence of a long-term retention phase for individuals with no radioiodine concentrating tissue. The general purpose of this study was to develop a kinetic model and estimate the absorbed dose to athyroid individuals regarding the distribution and retention of NaI.

It is likely that the breast is the organ most sensitive to radiation carcinogenesis in postpubertal women. Studies of different exposed populations have yielded remarkably consistent results, in spite of wide differences in underlying breast cancer rates and conditions of exposure. Excess risk is approximately proportional to dose, and is relatively independent of ionization density and fractionization of dose. This implies that the risk associated with low-dose exposures to ionizing radiation can be estimated with some confidence from higher-dose data. Excess risk is heavily dependent on age at exposure but relatively independent of population differences in normal risk. The temporal patterns after exposure of both radiation-induced and naturally occurring breast cancer are similar, suggesting a strong influence of factors other than radiation on radiation-induced breast cancer. Uncertainties remain about risks from exposures before puberty and after menopause.

In vitro dose-response curves are used to describe the relation between the yield of dicentric chromosome aberrations and radiationdose for human lymphocytes. The dicentric yields follow the Poisson distribution, and the expected yield depends on both the magnitude and the temporal distribution of the dose for low LET radiation. A general dose-response model that describes this relation has been obtained by Kellerer and Rossi using the theory of dual radiation action. The yield of elementary lesions is kappa(..gamma..d + g(t, tau)d/sup 2/), where t is the time and d is dose. The coefficient of the d/sup 2/ term is determined by the recovery function and the temporal mode of irradiation. Two special cases of practical interest are split-dose and continuous exposure experiments, and the resulting models are intrinsically nonlinear in the parameters. A general purpose maximum likelihood estimation procedure is described and illustrated with numerical examples from both experimental designs. Poisson regression analysis is used for estimation, hypothesis testing, and regression diagnostics. Results are discussed in the context of exposure assessment procedures for both acute and chronic human radiation exposure.

Computed tomography (CT) scanning is recognised as a high-radiationdose modality and estimated to be 17 % of the radiological procedure and responsible for 70 % of medical radiation exposure. Although diagnostic X rays provide great benefits, their use involves some risk for developing cancer. The objectives of this study are to estimateradiationdoses during chest, abdomen and pelvis CT. A total of 51 patients were examined for the evaluation of metastasis of a diagnosed primary tumour during 4 months. A calibrated CT machine from Siemens 64 slice was used. The mean age was 48.0 ± 18.6 y. The mean patient weight was 73.8 ± 16.1 kg. The mean dose-length product was 1493.8 ± 392.1 mGy cm, Volume CT dose index (CTDI vol) was 22.94 ± 5.64 mGy and the mean effective dose was 22.4 ± 5.9 mSv per procedure. The radiationdose per procedure was higher as compared with previous studies. Therefore, the optimisation of patient's radiationdoses is required in order to reduce the radiation risk. PMID:25852181

Accurate dosimetry is critically important for ecotoxicological and radioecological studies on the potential effects of environmentally relevant radionuclides, such as tritium ((3)H). Previous studies have used basic dosimetric equations to estimatedose from (3)H exposure in ecologically important organisms, such as marine mussels. This study compares four different methods of estimatingdose to adult mussels exposed to 1 or 15 MBq L(-1) tritiated water (HTO) under laboratory conditions. These methods were (1) an equation converting seawater activity concentrations to dose rate with fixed parameters; (2) input into the ERICA tool of seawater activity concentrations only; (3) input into the ERICA tool of estimated whole organism concentrations (woTACs), comprising dry activity plus estimated tissue free water tritium (TFWT) activity (TFWT volume × seawater activity concentration); and (4) input into the ERICA tool of measured whole organism activity concentrations, comprising dry activity plus measured TFWT activity (TFWT volume × TFWT activity concentration). Methods 3 and 4 are recommended for future ecotoxicological experiments as they produce values for individual animals and are not reliant on transfer predictions (estimation of concentration ratio). Method 1 may be suitable if measured whole organism concentrations are not available, as it produced results between 3 and 4. As there are technical complications to accurately measuring TFWT, we recommend that future radiotoxicological studies on mussels or other aquatic invertebrates measure whole organism activity in non-dried tissues (i.e. incorporating TFWT and dry activity as one, rather than as separate fractions) and input this data into the ERICA tool. PMID:26874225

This section of the 1994 Hanford Site Environmental Report summarizes the potential radiationdoses to the public from releases originating at the Hanford Site. Members of the public are potentially exposed to low-levels of radiation from these effluents through a variety of pathways. The potential radiationdoses to the public were calculated for the hypothetical MEI and for the general public residing within 80 km (50 mi) of the Hanford Site.

The Bayesian framework has been shown to be very useful in cytogenetic doseestimation. This approach allows description of the probability of an event in terms of previous knowledge, e.g. its expectation and/or its uncertainty. A new R package entitled radir (radiation inverse regression) has been implemented with the aim of reproducing a recent Bayesian-type doseestimation methodology. radir adopts the method of doseestimation under the Poisson assumption of the responses (the chromosomal aberrations counts) for the required dose-response curve (typically linear or quadratic). The individual commands are described in detail and relevant examples of the use of the methods and the corresponding radir software tools are given. The suitability of this methodology is highlighted and its application encouraged by providing a user-friendly command-type software interface within the R statistical software (version 3.1.1 or higher), which includes a complete manual. PMID:26160852

A study is underway to develop an approach to quantify bias and uncertainty in recorded doseestimates for workers at the Hanford Site based on personnel dosimeter results. This paper focuses on selected experimental studies conducted to better define response characteristics of Hanford dosimeters. The study is more extensive than the experimental studies presented in this paper and includes detailed consideration and evaluation of other sources of bias and uncertainty. Hanford worker doseestimates are used in epidemiologic studies of nuclear workers. A major objective of these studies is to provide a direct assessment of the carcinogenic risk of exposure to ionizing radiation at low doses and dose rates. Considerations of bias and uncertainty in the recorded doseestimates are important in the conduct of this work. The method developed for use with Hanford workers can be considered an elaboration of the approach used to quantify bias and uncertainty in estimateddoses for personnel exposed to radiation as a result of atmospheric testing of nuclear weapons between 1945 and 1962. This approach was first developed by a National Research Council (NRC) committee examining uncertainty in recorded film badge doses during atmospheric tests (NRC 1989). It involved quantifying both bias and uncertainty from three sources (i.e., laboratory, radiological, and environmental) and then combining them to obtain an overall assessment. Sources of uncertainty have been evaluated for each of three specific Hanford dosimetry systems (i.e., the Hanford two-element film dosimeter, 1944-1956; the Hanford multi-element film dosimeter, 1957-1971; and the Hanford multi-element TLD, 1972-1993) used to estimate personnel dose throughout the history of Hanford operations. Laboratory, radiological, and environmental sources of bias and uncertainty have been estimated based on historical documentation and, for angular response, on selected laboratory measurements.

The research reported in this document was conducted as a part of the Hanford Environmental Dose Reconstruction (HEDR) Project. The objective of the HEDR Project is to estimate the radiationdoses that people could have received from operations at the Hanford Site. Information required to estimate these doses includes estimates of the amounts of potentially contaminated foods that individuals in the region consumed during the study period. In that general framework, the objective of the Food Consumption Task was to develop a capability to provide information about the parameters of the distribution(s) of daily food consumption for representative groups in the population for selected years during the study period. This report describes the methods and data used to estimate food consumption and presents the results developed for Phase I of the HEDR Project.

Interventional cardiology procedures result in substantial patient radiationdoses due to prolonged fluoroscopy time and radiographic exposure. The procedures that are most frequently performed are coronary angiography, percutaneous coronary interventions, diagnostic electrophysiology studies and radiofrequency catheter ablation. Patient radiationdose in these procedures can be assessed either by measurements on a series of patients in real clinical practice or measurements using patient-equivalent phantoms. In this article we review the derived doses at non-pediatric patients from 72 relevant studies published during the last 22 years in international scientific literature. Published results indicate that patient radiationdoses vary widely among the different interventional cardiology procedures but also among equivalent studies. Discrepancies of the derived results are patient-, procedure-, physician-, and fluoroscopic equipmentrelated. Nevertheless, interventional cardiology procedures can subject patients to considerable radiationdoses. Efforts to minimize patient exposure should always be undertaken. PMID:20066141

Digital subtraction angiography (DSA) is a type of fluoroscopy technique used in interventional radiology to clearly visualize blood vessels in a bony or dense soft tissue environment. The use of DSA procedures has been increased quite significantly in the Radiology departments in various cities in Indonesia. Various reports showed that both patients and medical staff received a noticeable radiationdose during the course of this procedure. A study had been carried out to measure these doses among interventionalist, nurse and radiographer. The results show that the interventionalist and the nurse, who stood quite close to the X-ray beams compared with the radiographer, received radiation higher than the others. The results also showed that the radiationdose received by medical staff were var depending upon the duration and their position against the X-ray beams. Compared tothe dose limits, however, the radiationdose received by all these three medical staff were still lower than the limits.

The determination of dose conversion factors (S values) for the radionuclide fluorodeoxyglucose (18F-FDG) absorbed in the lungs during a positron emission tomography (PET) procedure was calculated using the Monte Carlo method (MCNPX version 2.7.0). For the obtained dose conversion factors of interest, it was considered a uniform absorption of radiopharmaceutical by the lung of a healthy adult human. The spectrum of fluorine was introduced in the input data file for the simulation. The simulation took place in two adult phantoms of both sexes, based on polygon mesh surfaces called FASH and MASH with anatomy and posture according to ICRP 89. The S values for the 22 internal organs/tissues, chosen from ICRP No. 110, for the FASH and MASH phantoms were compared with the results obtained from a MIRD V phantoms called ADAM and EVA used by the Committee on Medical Internal RadiationDose (MIRD). We observed variation of more than 100% in S values due to structural anatomical differences in the internal organs of the MASH and FASH phantoms compared to the mathematical phantom.

Radiation processing relies to a large extent on dosimetry as control of proper operation. This applies in particular to radiation sterilization of medical products and food treatment, but also during development of any other process. The assurance that proper dosimetry is performed at the radiation processing plant can be obtained through the mediation of an international organization, and the IAEA is now implementing a dose assurance service for industrial radiation processing.

Radiation therapy is one of the important treatment procedures of cancer. The day-to-day delivered dose to the tissue in radiation therapy often deviates from the planned fixed dose per fraction. This day-to-day variation of radiationdose is stochastic. Here, we have developed the mathematical formulation to represent the day-to-day stochastic dose variation effect in radiation therapy. Our analysis shows that that the fixed dose delivery approximation under-estimates the biological effective dose, even if the average delivered dose per fraction is equal to the planned dose per fraction. The magnitude of the under-estimation effect relies upon the day-to-day stochastic dose variation level, the dose fraction size and the values of the radiobiological parameters of the tissue. We have further explored the application of our mathematical formulation for adaptive dose calculation. Our analysis implies that, compared to the premise of the Linear Quadratic Linear (LQL) framework, the Linear Quadratic framework based analytical formulation under-estimates the required dose per fraction necessary to produce the same biological effective dose as originally planned. Our study provides analytical formulation to calculate iso-effect in adaptive radiation therapy considering day-to-day stochastic dose deviation from planned dose and also indicates the potential utility of LQL framework in this context. PMID:26776265

The relevant national and international guidance concerning the estimation of radiological doses from the practice of deepsea disposal of radioactive waste was reviewed. The review includes the dose limitation guidance of the various national and international bodies, especially that of the International Commission on Radiological Protection (ICRP). Pathway modeling is discussed as well as the oceanographic models of the International Atomic Energy Agency (IAEA). Included in the discussion are the recommendations for the definition of high-level waste by the IAEA for use by the London Dumping Convention (LDC) in setting limits for ocean disposal of waste. An assessment of the ICRP's radiological protection system using the effective whole-body dose methodology is made. Present models, which should continue to be improved as the research data becomes available, do provide an adequate basis for regulatory authorities to decide whether authorization for a proposed disposal can be granted, since they provide a means of indicating whether maximum individual (critical groups) exposure limits are likely to be exceeded. However, new models and information are continuously being developed by the international community to assess ocean disposal of radioactive waste in comparison to land disposal and to compare one site against another. 47 refs., 2 figs., 4 tabs.

Explains how x-ray doses to patients are measured. Describes how different techniques expose patients to differing amounts of ionizing radiation. Compares these figures with other natural and man-made sources. (Author/MKR)

Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096±0.019(1 SD) and 0.092±0.016(1 SD)μSv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11±0.042(1 SD) and 0.091±0.026(1 SD)μSv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, 222Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

Gamma dose rate measurements were performed in one urban and one rural area using thermoluminescence dosimeters (TLD) worn by 46 participants and placed in their dwellings. The personal effective dose rates were 0.096{+-}0.019(1 SD) and 0.092{+-}0.016(1 SD){mu}Sv/h in the urban and rural area, respectively. The corresponding dose rates in the dwellings were 0.11{+-}0.042(1 SD) and 0.091{+-}0.026(1 SD){mu}Sv/h. However, the differences between the areas were not significant. The values were higher in buildings made of concrete than of wood and higher in apartments than in detached houses. Also, {sup 222}Rn measurements were performed in each dwelling, which showed no correlation with the gamma dose rates in the dwellings.

Absorption of energy from ionizing radiation by the genetic material in the cell leads to damage to DNA, which in turn leads to cell death, chromosome aberrations and gene mutations. While early or deterministic effects result from organ and tissue damage caused by cell killing, latter two are considered to be involved in the initial events that lead to the development of cancer. Epidemiological studies have demonstrated the dose-response relationships for cancer induction and quantitative evaluations of cancer risk following exposure to moderate to high doses of low-linear energy transfer radiation. A linear, no-threshold model has been applied to assessment of the risks resulting from exposure to moderate and high doses of ionizing radiation; however, a statistically significant increase has hardly been described for radiationdoses below 100 mSv. This review summarizes our current knowledge of the physical and biological features of low-doseradiation and discusses the possibilities of induction of cancer by low-doseradiation. PMID:22641644

This paper assesses the individual and collective doses in Ireland due to cosmic radiation. Information on the exposure to cosmic radiation at ground level is reviewed and published data on the frequency of routes flown by Irish residents is used to calculate the dose due to air travel. Occupational exposure of aircrew is also evaluated. Experimental data on cosmic radiation exposure at ground level is in good agreement with international estimates and the average individual dose is calculated as 300 microSv annually. Published data on international air travel by Irish residents shows a 50% increase in the number of flights taken between 2001 and 2005. This increase is primarily on short-haul flights to Europe, but there have been significant percentage increases in all long-haul flights, with the exception of flights to Africa. The additional per capita dose due to air travel is estimated to be 45 muSv, of which 51% is accumulated on European routes and 34% on routes to the United States. Exposure of aircrew to cosmic radiation is now controlled by legislation and all airlines holding an Air Operator's Certificate issued by the Irish Aviation Authority are required to report annually the doses received by their employees in the previous year. There has been a 75% increase in the number of aircrew receiving doses >1 mSv since 2002. In 2004 and 2005 the average individual doses received by Irish aircrew were 1.8 and 2.0, mSv, respectively. The corresponding per caput dose for the entire population is <3 muSv. While this is low compared with the per caput doses from other sources of cosmic radiation, aircrew exposure represents a higher collective dose than any other identified group of exposed workers in Ireland. PMID:17223639

ERDEM is a physiologically-based pharmacokinetic (PBPK) model with a graphical user interface (GUI) front end. Such a mathematical model was needed to make reliable estimates of the chemical dose to organs of animals or humans because of uncertainties of making route-to route, lo...

The demand of interventional radiology has increased, leading to significant risk of radiation where eye lens dose assessment becomes a major concern. In this study, we investigate physicians' eye lens doses during interventional procedures. Measurement were made using TLD-100 (LiF: Mg, Ti) dosimeters and was recorded in equivalent dose at a depth of 0.07 mm, Hp(0.07). Annual Hp(0.07) and annual effective dose were estimated using workload estimation for a year and Von Boetticher algorithm. Our results showed the mean Hp(0.07) dose of 0.33 mSv and 0.20 mSv for left and right eye lens respectively. The highest estimated annual eye lens dose was 29.33 mSv per year, recorded on left eye lens during fistulogram procedure. Five physicians had exceeded 20 mSv dose limit as recommended by international commission of radiological protection (ICRP). It is suggested that frequent training and education on occupational radiation exposure are necessary to increase knowledge and awareness of the physicians’ thus reducing dose during the interventional procedure.

Radiationdoses to individuals were estimated for the years 1944-1992. The doseestimates were based on the radioactive-releases from the Hanford Site in south central Washington. Conceptual models and computer codes were used to reconstruct doses through the early 1970s. The published Hanford Site annual environmental data were used to complete the does history through 1992. The most significant exposure pathway was found to be the consumption of cow`s milk containing iodine-131. For the atmospheric pathway, median cumulative doseestimates to the thyroid of children ranged from < 0.1 to 235 rad throughout the area studied. The geographic distribution of the dose levels was directly related to the pattern of iodine-131 deposition and was affected by the distribution of commercial milk and leafy vegetables. For the atmospheric pathway, the-highest estimated cumulative-effective-dose-equivalent (EDE) to an adult was estimated to be 1 rem at Ringold, Washington for the period 1944-1992. For the Columbia River pathway, cumulative EDE estimates ranged from <0.5 to l.5 rem cumulative dose to maximally exposed adults downriver from the Hanford Site for the years 1944-1992. The most significant river exposure pathway was consumption of resident fish containing phosphorus-32 and zinc-65.

In a biological assay the expected response may be transformed to a variable bounded between 0 and 1. If the transformed response is regarded as analogous to the tolerance distribution function, the mean of that distribution may be estimated for the standard and test preparations, and a simple estimator of the relative potency obtained. The special case where the identity transformation is used for a quantal response corresponds to Spearman's estimator, and our generalization has similar unbiasedness properties to that estimator. Asymptotic results are derived when the intervals between dose levels decrease and the sample of each dose level simultaneously increases. These results are evaluated for the case with equal sample sizes at regularly spaced values of the dose metameter. An approximate test for similarity is proposed. If the tolerance distribution is known up to a scale parameter, then the transformation may be chosen so that the estimator is asymptotically fully efficient. An application to the thermal disinfestation of wheat is given. PMID:7272411

Synopsis As a result of the changes in utilization of imaging procedures that rely on ionizing radiation, the collective dose has increased by over 700% and the annual per-capita dose, by almost 600% over recent years. It is certainly possible that this growing use may have significant effects on public health. Although there are uncertainties related to the accuracy of calculated radiation exposure and the estimated biologic risk, there are measures that can be taken to reduce any potential risks while maintaining diagnostic accuracy. This article will review the existing data regarding biological hazards of radiation exposure associated to medical diagnostic testing, the methodology used to estimateradiation exposure and the measures that can be taken to effectively reduce it. PMID:19766923

This paper describes sources of uncertainty in the data used for calculating doseestimates for the Hiroshima explosion and details a methodology for systematically obtaining best estimates and reduced uncertainties for the radiationdoses received. (ACR)

The National Aeronautics and Space Administration (NASA) performs organ dosimetry and risk assessment for astronauts using model-normalized measurements of the radiation fields encountered in space. To determine the radiation fields in an organ or tissue of interest, particle transport calculations are performed using self-shielding distributions generated with the computer program CAMERA to represent the human body. CAMERA mathematically traces linear rays (or path lengths) through the computerized anatomical man (CAM) phantom, a computational stylized model developed in the early 1970s with organ and body profiles modeled using solid shapes and scaled to represent the body morphometry of the 1950 50th percentile (PCTL) Air Force male. With the increasing use of voxel phantoms in medical and health physics, a conversion from a mathematical-based to a voxel-based ray-tracing algorithm is warranted. In this study, the voxel-based ray tracer (VoBRaT) is introduced to ray trace voxel phantoms using a modified version of the algorithm first proposed by Siddon (1985 Med. Phys. 12 252-5). After validation, VoBRAT is used to evaluate variations in body self-shielding distributions for NASA phantoms and six University of Florida (UF) hybrid phantoms, scaled to represent the 5th, 50th, and 95th PCTL male and female astronaut body morphometries, which have changed considerably since the inception of CAM. These body self-shielding distributions are used to generate organ dose equivalents and effective doses for five commonly evaluated space radiation environments. It is found that dosimetric differences among the phantoms are greatest for soft radiation spectra and light vehicular shielding.

The purpose of this work was to determine the radiation tolerance of the lens of the eye and the incidence of radiation-induced lens changes in patients treated by fractionated supervoltage radiation therapy for orbital tumors. Forty patients treated for orbital lymphoma and pseudotumor with tumor doses of 20--40 Gy were studied. The lens was partly shielded using lead cylinders in most cases. The dose to the germinative zone of the lens was estimated by measurements in a tissue equivalent phantom using both film densitometry and thermoluminescent dosimetry. Opthalmological examination was performed at 6 monthly intervals after treatment. The lead shield was found to reduce the dose to the germinative zone of the lens to between 36--50% of the tumor dose for Cobalt beam therapy, and to between 11--18% for 5 MeV x-rays. Consequently, the lens doses were in the range 4.5--30 Gy in 10--20 fractions. Lens opacities first appeared from between 3 and 9 years after irradiation. Impairment of visual acuity ensued in 74% of the patients who developed lens opacities. The incidence of lens changes was strongly dose-related. None was seen after doses of 5 Gy or lower, whereas doses of 16.5 Gy or higher were all followed by lens opacities which impaired visual acuity. The largest number of patients received a maximum lens dose of 15 Gy; in this group the actuarial incidence of lens opacities at 8 years was 57% with visual impairment in 38%. The adult lens can tolerate a total dose of 5 Gy during a fractionated course of supervoltage radiation therapy without showing any changes. Doses of 16.5 Gy or higher will almost invariably lead to visual impairment. The dose which causes a 50% probability of visual impairment is approximately 15 Gy. 10 refs., 4 figs., 1 tab.

Proton beam losses in various components of a treatment nozzle generate secondary neutrons, which bring unwanted out of field dose during treatments. The purpose of this study was to develop an analytic method for estimating neutron dose to a distant organ at risk during proton therapy. Based on radiation shielding calculation methods proposed by Sullivan, we developed an analytical model for converting the proton beam losses in the nozzle components and in the treatment volume into the secondary neutron dose at a point of interest. Using the MCNPx Monte Carlo code, we benchmarked the neutron dose rates generated by the proton beam stopped at various media. The Monte Carlo calculations confirmed the validity of the analytical model for simple beam stop geometry. The analytical model was then applied to neutron dose equivalent measurements performed on double scattering and uniform scanning nozzles at the Midwest Proton Radiotherapy Institute (MPRI). Good agreement was obtained between the model predictions and the data measured at MPRI. This work provides a method for estimating analytically the neutron dose equivalent to a distant organ at risk. This method can be used as a tool for optimizing dose delivery techniques in proton therapy.

The Monte Carlo method enables accurate dose calculation for radiation therapy treatment planning and has been implemented in some commercial treatment planning systems. Unlike conventional dose calculation algorithms that provide patient dose information in terms of dose to water with variable electron density, the Monte Carlo method calculates the energy deposition in different media and expresses dose to a medium. This paper discusses the differences in dose calculated using water with different electron densities and that calculated for different biological media and the clinical issues on dose specification including dose prescription and plan evaluation using dose to water and dose to medium. We will demonstrate that conventional photon dose calculation algorithms compute doses similar to those simulated by Monte Carlo using water with different electron densities, which are close (<4% differences) to doses to media but significantly different (up to 11%) from doses to water converted from doses to media following American Association of Physicists in Medicine (AAPM) Task Group 105 recommendations. Our results suggest that for consistency with previous radiation therapy experience Monte Carlo photon algorithms report dose to medium for radiotherapy dose prescription, treatment plan evaluation and treatment outcome analysis. PMID:21508447

A radiationdose-rate monitor is provided which operates in a conventional linear mode for radiation in the 0 to 0.5 R/h range and utilizes a nonlinear mode of operation for sensing radiation from 0.5 R/h to over 500 R/h. The nonlinear mode is achieved by a feedback circuit which adjusts the high voltage bias of the proportional counter, and hence its gas gain, in accordance with the amount of radiation being monitored. This allows compression of readout onto a single scale over the range of 0 to greater than 500 R/h without scale switching operations.

A radiationdose-rate monitor is provided which operates in a conventional linear mode for radiation in the 0 to 0.5 R/h range and utilizes a nonlinear mode of operation for sensing radiation from 0.5 R/h to over 500 R/h. The nonlinear mode is achieved by a feedback circuit which adjusts the high voltage bias of the proportional counter, and hence its gas gain, in accordance with the amount of radiation being monitored. This allows compression of readout onto a single scale over the range of 0 to greater than 500 R/h without scale switching operations.

People with genetic cancer syndromes have a special interest in imaging. They also have special risk factors with respect to radiation. They need to utilize the potential of imaging while keeping in mind concerns about cumulative radiation exposure. Before imaging, early detection of problems was limited. With imaging, issues can be identified when they are small and a good plan of action can be developed early. Operations can be planned and metastatic cancer avoided. The positive contribution of imaging to the care of these patients can be profound. However, this additional surveillance is not without cost. An average patient with 1 of these syndromes will undergo 100 or more scans in their lifetime. Imaging professionals should be able to describe the risks and benefits of each scan in terms that the patient and the ordering physician can understand to make smart decisions about the ordering of scans. Why CT versus MRI? When are x-ray or ultrasound appropriate, and when are they not? What are the costs and the medical risks for the patient? What value does this picture add for the physician? Is there a way to answer the medical question with a test other than a scan? Medicine is a team sport, and the patient is an integral member of the team. PMID:24589397

Radiographic imaging systems can produce records of exposure and dose parameters for each patient. A variety of file formats are in use including plain text, bit map images showing pictures of written text and radiationdose structured reports as text or extended markup language files. Whilst some of this information is available with image data on the hospital picture archive and communication system, access is restricted to individual patient records, thereby making it difficult to locate multiple records for the same scan protocol. This study considers the exposure records and dose reports from four modalities. Exposure records for mammography and general radiography are utilized for repeat analysis. Dose reports for fluoroscopy and computed tomography (CT) are utilized to study the distribution of patient doses for each protocol. Results for dosimetric quantities measured by General Radiography, Fluoroscopy and CT equipment are summarised and presented in the Appendix. Projection imaging uses the dose (in air) area product and derived quantities including the dose to the reference point as a measure of the air kerma reaching the skin, ignoring movement of the beam for fluoroscopy. CT uses the dose indices CTDIvol and dose length product as a measure of the dose per axial slice, and to the scanned volume. Suitable conversion factors are identified and used to estimate the effective dose to an average size patient (for CT and fluoroscopy) and the entrance skin dose for fluoroscopy. PMID:25315104

A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiationdose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiationdose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with netruon-absorbing elements, energetic neutron dose can be estimated separately from other radiationdose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

Temporomandibular joint morphology and function can be evaluated by panoramic zonography. Thermoluminescent dosimetry was applied to evaluate the radiationdose to predetermined sites on a phantom eye, thyroid, pituitary, and parotid, and the dose distribution on the skin of the head and neck when the TMJ program of the Zonarc panoramic x-ray unit was used. Findings are discussed with reference to similar radiographic techniques.

BIOPORT/MAXI1 is a collection of five computer codes designed to estimate the potential magnitude of the radiationdose to man resulting from biotic transport processes. Dose to man is calculated for ingestion of agricultural crops grown in contaminated soil, inhalation of resuspended radionuclides, and direct exposure to penetrating radiation resulting from the radionuclide concentrations established in the available soil surface by the biotic transport model. This document is designed as both an instructional and reference document for the BIOPORT/MAXI1 computer software package and has been written for two major audiences. The first audience includes persons concerned with the mathematical models of biological transport of commercial low-level radioactive wastes and the computer algorithms used to implement those models. The second audience includes persons concerned with exercising the computer program and exposure scenarios to obtain results for specific applications. The report contains sections describing the mathematical models, user operation of the computer programs, and program structure. Input and output for five sample problems are included. In addition, listings of the computer programs, data libraries, and dose conversion factors are provided in appendices.

The distributions of radiationdose for stereotactic radiosurgery, using a modified linear accelerator (Philips SL-25 and SRS-200), have been studied by using three different dosimeters: (1) ferrous-agarose-xylenol orange (FAX) gels, (2) TLD, and (3) thick-emulsion GafChromic dye film. These dosimeters were loaded into a small volume of defect in a phantom head. A regular linac stereotactic radiosurgery treatment was then given to the phantom head for each type of dosimeter. The measured radiationdose and its distributions were found to be in good agreement with those calculated by the treatment planning computer. PMID:27421869

The overall hypothesis of this grant application is that the adaptive responses elicited by low dose ionizing radiation (LDIR) result in part from heritable DNA methylation changes in the epigenome. In the final budget period at the University of Wisconsin-Madison, we will specifically address this hypothesis by determining if the epigenetically labile, differentially methylated regions (DMRs) that regulate parental-specific expression of imprinted genes are deregulated in agouti mice by low doseradiation exposure during gestation. This information is particularly important to ascertain given the 1) increased human exposure to medical sources of radiation; 2) increased number of people predicted to live and work in space; and 3) enhanced citizen concern about radiation exposure from nuclear power plant accidents and terrorist ‘dirty bombs.’

The major goals of this program were to study the efficacy of low dose rate radiation exposures for the induction of acute myeloid leukemia (AML) and to characterize the leukemias that are caused by radiation exposures at low dose rate. An irradiator facility was designed and constructed that allows large numbers of mice to be irradiated at low dose rates for protracted periods (up to their life span). To the best of our knowledge this facility is unique in the US and it was subsequently used to study radioprotectors being developed for radiological defense (PLoS One. 7(3), e33044, 2012) and is currently being used to study the role of genetic background in susceptibility to radiation-induced lung cancer. One result of the irradiation was expected; low dose rate exposures are ineffective in inducing AML. However, another result was completely unexpected; the irradiated mice had a very high incidence of hepatocellular carcinoma (HCC), approximately 50%. It was unexpected because acute exposures are ineffective in increasing HCC incidence above background. This is a potential important finding for setting exposure limits because it supports the concept of an 'inverse dose rate effect' for some tumor types. That is, for the development of some tumor types low dose rate exposures carry greater risks than acute exposures.

Different radon measurement methods were applied in the old and new buildings of the Turkish bath of Eger, Hungary, in order to elaborate a radon measurement protocol. Besides, measurements were also made concerning the radon and thoron short-lived decay products, gamma dose from external sources and water radon. The most accurate results for doseestimation were provided by the application of personal radon meters. Estimated annual effective doses from radon and its short-lived decay products in the old and new buildings, using 0.2 and 0.1 measured equilibrium factors, were 0.83 and 0.17 mSv, respectively. The effective dose from thoron short-lived decay products was only 5 % of these values. The respective external gamma radiation effective doses were 0.19 and 0.12 mSv y(-1). Effective dose from the consumption of tap water containing radon was 0.05 mSv y(-1), while in the case of spring water, it was 0.14 mSv y(-1). PMID:21450699

The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

The radiation risk to astronauts has always been based on measurements using passive thermoluminescent dosimeters (TLDs). The skin dose is converted to dose equivalent using an average radiation quality factor based on model calculations. The radiological risk estimates, however, are based on organ and tissue doses. This paper describes results from the first space flight (STS-91, 51.65 degrees inclination and approximately 380 km altitude) of a fully instrumented Alderson Rando phantom torso (with head) to relate the skin dose to organ doses. Spatial distributions of absorbed dose in 34 1-inch-thick sections measured using TLDs are described. There is about a 30% change in dose as one moves from the front to the back of the phantom body. Small active dosimeters were developed specifically to provide time-resolved measurements of absorbed dose rates and quality factors at five organ locations (brain, thyroid, heart/lung, stomach and colon) inside the phantom. Using these dosimeters, it was possible to separate the trapped-proton and the galactic cosmic radiation components of the doses. A tissue-equivalent proportional counter (TEPC) and a charged-particle directional spectrometer (CPDS) were flown next to the phantom torso to provide data on the incident internal radiation environment. Accurate models of the shielding distributions at the site of the TEPC, the CPDS and a scalable Computerized Anatomical Male (CAM) model of the phantom torso were developed. These measurements provided a comprehensive data set to map the dose distribution inside a human phantom, and to assess the accuracy and validity of radiation transport models throughout the human body. The results show that for the conditions in the International Space Station (ISS) orbit during periods near the solar minimum, the ratio of the blood-forming organ dose rate to the skin absorbed dose rate is about 80%, and the ratio of the dose equivalents is almost one. The results show that the GCR model dose

Current methods for organ and effective doseestimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ dose for

The Juno mission to Jupiter will have a highly elliptical orbit taking the spacecraft through the radiation belts surrounding the planet. During these passes through the radiation belts, the spacecraft will be subject to high doses of radiation from energetic electrons and protons with energies ranging from 10 keV to 1 GeV. While shielding within the spacecraft main body will reduce the total absorbed dose to much of the spacecraft electronics, instruments and cables on the outside of the spacecraft will receive much higher levels of absorbed dose. In order to estimate the amount of degradation to two such cables, testing has been performed on two coaxial cables intended to provide high voltages to three of the instruments on Juno. Both cables were placed in a vacuum of 5x10(exp -6) torr and cooled to -50(deg)C prior to exposure to the radiation sources. Measurements of the coaxial capacitance per unit length and partial discharge noise floor indicate that increasing levels of radiation make measurable but acceptably small changes to the F EP Teflon utilized in the construction of these cables. In addition to the radiationdose testing, observations were made on the internal electrostatic charging characteristics of these cables and multiple discharges were recorded.

The Juno mission to Jupiter will have a highly elliptical orbit taking the spacecraft through the radiation belts surrounding the planet. During these passes through the radiation belts, the spacecraft will be subject to high doses of radiation from energetic electrons and protons with energies ranging from 10 keV to 1 GeV. While shielding within the spacecraft main body will reduce the total absorbed dose to much of the spacecraft electronics, instruments and cables on the outside of the spacecraft will receive much higher levels of absorbed dose. In order to estimate the amount of degradation to two such cables, testing has been performed on two coaxial cables intended to provide high voltages to three of the instruments on Juno. Both cables were placed in a vacuum of 5x10-6 torr and cooled to -50 C prior to exposure to the radiation sources. Measurements of the coaxial capacitance per unit length and partial discharge noise floor indicate that increasing levels of radiation make measurable but acceptably small changes to the F EP Teflon utilized in the construction of these cables. In addition to the radiationdose testing, observations were made on the internal electrostatic charging characteristics of these cables and multiple discharges were recorded.

The problems addressed are the protection of uranium mill workers from occupational exposure to uranium through routine bioassay programs and the assessment of accidental worker exposures. Comparisons of chemical properties and the biological behavior of refined uranium ore (yellowcake) are made to identify important properties that influence uranium distribution patterns among organs. These studies will facilitate calculations of organ doses for specific exposures and associated health risk estimates and will identify important bioassay procedures to improve evaluations of human exposures. A quantitative analytical method for yellowcake was developed based on the infrared absorption of ammonium diuranate and U/sub 3/O/sub 8/ mixtures in KBr. The method was applied to yellowcake samples obtained from six operating mills. The composition of yellowcake from the six mills ranged from nearly pure ammonium diuranate to nearly pure U/sub 3/O/sub 8/. The composition of yellowcake samples taken from lots from the same mill was only somewhat less variable. Because uranium mill workers might be exposed to yellowcake either by contamination of a wound or by inhalation, a study of retention and translocation of uranium after subcutaneous implantation in rats was done. The results showed that 49% of the implanted yellowcake cleared from the body with a half-time (T sub 1/2) in the body of 0.3 days, and the remainder was cleared with a T sub 1/2 of 11 to 30 days. Exposures of Beagle dogs by nose-only inhalation to aerosols of commercial yellowcake were completed. Biochemical indicators of kidney dysfunction that appeared in blood and urine 4 to 8 days after exposure to the more soluble yellowcake showed significant changes in dogs, but levels returned to normal by 16 days after exposure. No biochemical evidence of kidney dysfunction was observed in dogs exposed to the less soluble yellowcake form. 18 figures, 9 tables.

The standard quantity used to relate breast surface exposure to radiation risk is the mean dose received by the radiation sensitive tissue contained within the female breast, the mean glandular dose (MGD). At present, little is known about the MGD received by women with breast implants as there is no technique available to facilitate its calculation. The present work has involved modification of the conventional method for MGD estimation to make it applicable to women with augmented breasts. The technique was used to calculate MGDs for a cohort of 80 women with breast implants, which were compared with similar data calculated for a total of 1258 non-augmented women. Little difference was found in median MGD at low compressed breast thickness. At high breast thickness, however, the MGDs received by women with augmented breasts were found to be considerably lower than those relating to their non-augmented counterparts.

Genomic instability is a term used to describe a phenomenon that results in the accumulation of multiple changes required to convert a stable genome of a normal cell to an unstable genome characteristic of a tumor. There has been considerable recent debate concerning the importance of genomic instability in human cancer and its temporal occurrence in the carcinogenic process. Radiation is capable of inducing genomic instability in mammalian cells and instability is thought to be the driving force responsible for radiation carcinogenesis. Genomic instability is characterized by a large collection of diverse endpoints that include large-scale chromosomal rearrangements and aberrations, amplification of genetic material, aneuploidy, micronucleus formation, microsatellite instability, and gene mutation. The capacity of radiation to induce genomic instability depends to a large extent on radiation quality or linear energy transfer (LET) and dose. There appears to be a low dose threshold effect with low LET, beyond which no additional genomic instability is induced. Low doses of both high and low LET radiation are capable of inducing this phenomenon. This report reviews data concerning dose rate effects of high and low LET radiation and their capacity to induce genomic instability assayed by chromosomal aberrations, delayed lethal mutations, micronuclei and apoptosis.

Background There is concern over ionizing radiation exposure in women who are pregnant or of child-bearing age. Due to the increasing prevalence of congenital and acquired heart disease, the number of women who require cardiac interventions during pregnancy has increased. We have developed protocols for cardiac interventions in pregnant women and women of child-bearing age, aimed at substantially reducing both fluoroscopy duration and radiationdoses. Methods Over five years, we performed cardiac interventions on 15 pregnant women, nine postpartum women and four as part of prepregnancy assessment. Fluoroscopy times were minimized by simultaneous use of intracardiac echocardiography, and by using very low frame rates (2/second) during fluoroscopy. Results The procedures most commonly undertaken were closure of atrial septal defect (ASD) or patent foramen ovale (PFO) in 16 women, coronary angiograms in seven, right and left heart catheters in three and two stent placements. The mean screening time for all patients was 2.38 minutes (range 0.48–13.7), the median radiationdose was 66 (8.9–1501) Gy/cm2. The median radiationdose to uterus was 1.92 (0.59–5.47) μGy, and the patient estimateddose was 0.24 (0.095–0.80) mSv. Conclusions Ionizing radiation can be used safely in the management of severe cardiac structural disease in pregnancy, with very low ionizing radiationdose to the mother and extremely low exposure to the fetus. With experience, ionizing radiationdoses at our institution have been reduced.

Synchrotron radiation is an innovative tool for the treatment of brain tumors. In the stereotactic synchrotron radiation therapy (SSRT) technique a radiationdose enhancement specific to the tumor is obtained. The tumor is loaded with a high atomic number (Z) element and it is irradiated in stereotactic conditions from several entrance angles. The aim of this work was to assess dosimetric properties of the SSRT for preparing clinical trials at the European Synchrotron Radiation Facility (ESRF). To estimate the possible risks, the doses received by the tumor and healthy tissues in the future clinical conditions have been calculated by using Monte Carlo simulations (PENELOPE code). The dose enhancement factors have been determined for different iodine concentrations in the tumor, several tumor positions, tumor sizes, and different beam sizes. A scheme for the dose escalation in the various phases of the clinical trials has been proposed. The biological equivalent doses and the normalized total doses received by the skull have been calculated in order to assure that the tolerance values are not reached.

The Department of Energy's Off-Site Radiation Exposure Review Project has the goal of reconstructing both individual and population doses via all pathways including the ingestion and inhalation of radionuclides. As this is a reconstruction and not a prediction for safety purposes, the desired output is the best estimate of radiationdose with an appropriate expression of uncertainty. For the 80 events of interest, the data consistently available are external ..gamma.. exposure-rate measurements, measurements of airborne gross ..beta.. activity, and measurements of fission yield and of activation products created in the device environment. For most organs, the external ..gamma.. dose is much greater than the dose from ingestion which, in turn, is much greater than the dose from inhalation. The gastrointestinal tract may receive as large a dose from ingestion as from external exposure, depending upon dietary habits. The dose to the thyroid gland is usually dominated by ingestion and the dose from inhalation can be nearly as large as that from external exposure. Several example calculations are presented for specific individuals.

Radiation protection practices define the effective dose as a weighted sum of equivalent dose over major organ sites for radiation cancer risks. Since a crew personnel dosimeter does not make direct measurement of the effective dose, it has been estimated with skin-dose measurements and radiation transport codes for ISS and STS missions. If sufficient protection is not provided near solar maximum, the radiation risk can be significant due to exposure to sporadic solar particle events (SPEs) as well as to the continuous galactic cosmic radiation (GCR) on future exploratory-class and long-duration missions. For accurate estimates of overall fatal cancer risks from SPEs, the specific doses at various blood forming organs (BFOs) were considered, because proton fluences and doses vary considerably across marrow regions. Previous estimates of BFO doses from SPEs have used an average body-shielding distribution for the bone marrow based on the computerized anatomical man model (CAM). With the development of an 82-point body-shielding distribution at BFOs, the mean and variance of SPE doses in the major active marrow regions (head and neck, chest, abdomen, pelvis and thighs) will be presented. Consideration of the detailed distribution of bone marrow sites is one of many requirements to improve the estimation of effective doses for radiation cancer risks.

Background/Aim: Endoscopic retrograde cholangiopancreatography (ERCP) is associated with a considerable radiation exposure for patients and staff. While optimization of the radiationdose is recommended, few studies have been published. The purpose of this study has been to measure patient and staff radiationdose, to estimate the effective dose and radiation risk using digital fluoroscopic images. Entrance skin dose (ESD), organ and effective doses were estimated for patients and staff. Materials and Methods: Fifty-seven patients were studied using digital X-ray machine and thermoluminescent dosimeters (TLD) to measure ESD at different body sites. Organ and surface dose to specific radiosensitive organs was carried out. The mean, median, minimum, third quartile and the maximum values are presented due to the asymmetry in data distribution. Results: The mean ESD, exit and thyroid surface dose were estimated to be 75.6 mGy, 3.22 mGy and 0.80 mGy, respectively. The mean effective dose for both gastroenterologist and assistant is 0.01 mSv. The mean patient effective dose was 4.16 mSv, and the cancer risk per procedure was estimated to be 2 × 10-5 Conclusion: ERCP with fluoroscopic technique demonstrate improved dose reduction, compared to the conventional radiographic based technique, reducing the surface dose by a factor of 2, without compromising the diagnostic findings. The radiation absorbed doses to the different organs and effective doses are relatively low. PMID:21196649

Potential evapotranspiration (PET) is of great importance to estimation of surface energy budget and water balance calculation. The accurate estimation of PET will facilitate efficient irrigation scheduling, drainage design, and other agricultural and meteorological applications. However, accuracy o...

Dose as a result of radiation exposure is the notion generally used to disclose the imparted energy in a volume of tissue to a potential biological effect. The basic unit defined by the international system of units (SI system) is the radiation absorbed dose, which is expressed as the mean imparted energy in a mass element of the tissue known as "gray" (Gy) or J/kg. The procedure for ascertaining the absorbed dose is complicated since it involves the radiation transport of numerous types of charged particles and coupled photon interactions. The most precise method is to perform a full 3D Monte Carlo simulation of the radiation transport. There are various Monte Carlo toolkits that have tool compartments for dose calculations and measurements. The dose studies in this thesis were performed using the GEANT4 Application for Emission Tomography (GATE) software (Jan et al., 2011) GATE simulation toolkit has been used extensively in the medical imaging community, due to the fact that it uses the full capabilities of GEANT4. It also utilizes an easy to-learn GATE macro language, which is more accessible than learning the GEANT4/C++ programming language. This work combines GATE with digital phantoms generated using the NCAT (NURBS-based cardiac-torso phantom) toolkit (Segars et al., 2004) to allow efficient and effective estimation of 3D radiationdose maps. The GATE simulation tool has developed into a beneficial tool for Monte Carlo simulations involving both radiotherapy and imaging experiments. This work will present an overview of absorbed dose of common radionuclides used in nuclear medicine and serve as a guide to a user who is setting up a GATE simulation for a PET and SPECT study.

Stakeholders have raised numerous issues regarding the scientific basis of radiationdose reconstruction for compensation. These issues can be grouped into three broad categories: data issues, dosimetry issues, and compensation issues. Data issues include demographic data of the worker, changes in site operations over time (both production and exposure control), characterization of episodic vs. chronic exposures, and the use of coworker data. Dosimetry issues include methods for assessment of ambient exposures, missed dose, unmonitored dose, and medical x-ray dose incurred as a condition of employment. Specific issues related to external dose include the sensitivity, angular and energy dependence of personal monitors, exposure geometries, and the accompanying uncertainties. Those related to internal dose include sensitivity of bioassay methods, uncertainties in biokinetic models, appropriate dose coefficients, and modeling uncertainties. Compensation issues include uncertainties in the risk models and use of the 99th percentile of the distribution of probability of causation for awarding compensation. A review of the scientific literature and analysis of each of these issues distinguishes factors that play a major role in the compensation decision from those that do not. PMID:18545027

Ionizing radiation used in the patient diagnosis or therapy has negative effects on the patient body in short term and long term depending on the amount of exposure. More than 700,000 examinations are everyday performed on Interventional Radiology modalities, however; there is no patient-centric information available to the patient or the Quality Assurance for the amount of organ dose received. In this study, we are exploring the methodologies to systematically reduce the absorbed radiationdose in the Fluoroscopically Guided Interventional Radiology procedures. In the first part of this study, we developed a mathematical model which determines a set of geometry settings for the equipment and a level for the energy during a patient exam. The goal is to minimize the amount of absorbed dose in the critical organs while maintaining image quality required for the diagnosis. The model is a large-scale mixed integer program. We performed polyhedral analysis and derived several sets of strong inequalities to improve the computational speed and quality of the solution. Results present the amount of absorbed dose in the critical organ can be reduced up to 99% for a specific set of angles. In the second part, we apply an approximate gradient method to simultaneously optimize angle and table location while minimizing dose in the critical organs with respect to the image quality. In each iteration, we solve a sub-problem as a MIP to determine the radiation field size and corresponding X-ray tube energy. In the computational experiments, results show further reduction (up to 80%) of the absorbed dose in compare with previous method. Last, there are uncertainties in the medical procedures resulting imprecision of the absorbed dose. We propose a robust formulation to hedge from the worst case absorbed dose while ensuring feasibility. In this part, we investigate a robust approach for the organ motions within a radiology procedure. We minimize the absorbed dose for the critical

During proton radiotherapy, secondary neutrons are produced by nuclear interactions in the material along the beam path, in the treatment nozzle (including the fixed scatterer, range modulator, etc.) and, of course, after entering the patient. The dose equivalent deposited by these neutrons is usually not considered in routine treatment planning. In this study, there has been estimated the neutron dose in patient (in as well as around the target volume) during proton radiotherapy using scattering and scanning techniques. The proton induced neutrons (and photons) have been simulated in the simple geometry of the single scattering and the pencil beam scanning universal nozzles and in geometry of the plastic phantom (made of tissue equivalent material - RW3 - imitate the patient). In simulations of the scattering nozzle, different types of brass collimators have been used as well. Calculated data have been used as an approximation of the radiation field in and around the chosen/potential target volume in the patient (plastic phantom). For the dose equivalent evaluation, fluence-to-dose conversion factors from ICRP report have been employed. The results of calculated dose from neutrons in various distances from the spot for different treatment technique and for different energies of incident protons have been compared and evaluated in the context of the dose deposited in the target volume. This work was supported by RVO: 68407700 and Grant Agency of the CTU in Prague, grant No. SGS12/200/OHK4/3T/14.

In case of internal contamination with plutonium materials, a treatment with diethylene triamine pentaacetic acid (DTPA) can be administered in order to reduce plutonium body burden and consequently avoid some radiationdose. DTPA intravenous injections or inhalation can start almost immediately after intake, in parallel with urinary and fecal bioassay sampling for dosimetric follow-up. However, urine and feces excretion will be significantly enhanced by the DTPA treatment. As internal dose is calculated from bioassay results, the DTPA effect on excretion has to be taken into account. A common method to correct bioassay data is to divide it by a factor representing the excretion enhancement under DTPA treatment by intravenous injection. Its value may be based on a nominal reference or observed after a break in the treatment. The aim of this study was to estimate the influence of this factor on internal dose by comparing the doseestimated using default or upper and lower values of the enhancement factor for 11 contamination cases. The observed upper and lower values of the enhancement factor were 18.7 and 63.0 for plutonium and 24.9 and 28.8 for americium. For americium, a default factor of 25 is proposed. This work demonstrates that the use of a default DTPA enhancement factor allows the determination of the magnitude of the contamination because doseestimated could vary by a factor of 2 depending on the value of the individual DTPA enhancement factor. In case of significant intake, an individual enhancement factor should be determined to obtain a more reliable dose assessment. PMID:27115221

Amongst 14,000 women with breast cancer treated between 1946 and 1982, 194 developed a second primary tumour in the contralateral breast more than one year after diagnosis of the first primary. The radiationdose to the contralateral breast was calculated for each member of this group and also for members of a control group matched for age, year of diagnosis and survival time. Comparison of the groups provides no evidence for radiation induced carcinogenesis on the contralateral breast in these patients. PMID:4041361

...) MISCELLANEOUS GUIDANCE FOR THE DETERMINATION AND REPORTING OF NUCLEAR RADIATIONDOSE FOR DOD PARTICIPANTS IN THE... of the radiation environment to which the veteran was exposed and shall include inhaled, ingested... claimant's reconstructed dose? (e) Is there any recorded radiation exposure for the individual? Does...

Purpose: Whole breast irradiation with deep-inspiration breath-hold (DIBH) technique among left-sided breast cancer patients significantly reduces cardiac irradiation; however, a potential disadvantage is increased incidental irradiation of the contralateral breast. Methods and Materials: Contralateral breast dose (CBD) was calculated by comparing 400 treatment plans of 200 left-sided breast cancer patients whose tangential fields had been planned on gated and nongated CT data sets. Various anatomic and field parameters were analyzed for their impact on CBD. For a subgroup of patients (aged {<=}45 years) second cancer risk in the contralateral breast (CB) was modeled by applying the linear quadratic model, compound models, and compound models considering dose-volume information (DVH). Results: The mean CBD was significantly higher in DIBH with 0.69 Gy compared with 0.65 Gy in normal breathing (P=.01). The greatest impact on CBD was due to a shift of the inner field margin toward the CB in DIBH (mean 0.4 cm; range, 0-2), followed by field size in magnitude. Calculation with different risk models for CBC revealed values of excess relative risk/Gy ranging from 0.48-0.65 vs 0.46-0.61 for DIBH vs normal breathing, respectively. Conclusion: Contralateral breast dose, although within a low dose range, was mildly but significantly increased in 200 treatment plans generated under gated conditions, predominately due to a shift in the medial field margin. Risk modeling for CBC among women aged {<=}45 years also pointed to a higher risk when comparing DIBH with normal breathing. This risk, however, was substantially lower in the model considering DVH information. We think that clinical decisions should not be affected by this small increase in CBD with DIBH because DIBH is effective in reducing the dose to the heart in all patients.

An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

Purpose: To characterize the radiationdose-response of the human spinal cord. Methods and Materials: Because no single institution has sufficient data to establish a dose-response function for the human spinal cord, published reports were combined. Requisite data were dose and fractionation, number of patients at risk, number of myelopathy cases, and survival experience of the population. Eight data points for cervical myelopathy were obtained from five reports. Using maximum likelihood estimation correcting for the survival experience of the population, estimates were obtained for the median tolerance dose, slope parameter, and {alpha}/{beta} ratio in a logistic dose-response function. An adequate fit to thoracic data was not possible. Hyperbaric oxygen treatments involving the cervical cord were also analyzed. Results: The estimate of the median tolerance dose (cervical cord) was 69.4 Gy (95% confidence interval, 66.4-72.6). The {alpha}/{beta} = 0.87 Gy. At 45 Gy, the (extrapolated) probability of myelopathy is 0.03%; and at 50 Gy, 0.2%. The dose for a 5% myelopathy rate is 59.3 Gy. Graphical analysis indicates that the sensitivity of the thoracic cord is less than that of the cervical cord. There appears to be a sensitizing effect from hyperbaric oxygen treatment. Conclusions: The estimate of {alpha}/{beta} is smaller than usually quoted, but values this small were found in some studies. Using {alpha}/{beta} = 0.87 Gy, one would expect a considerable advantage by decreasing the dose/fraction to less than 2 Gy. These results were obtained from only single fractions/day and should not be applied uncritically to hyperfractionation.

Slide rules are improved for estimatingdoses and dose rates resulting from nuclear criticality accidents. The original slide rules were created for highly enriched uranium solutions and metals using hand calculations along with the decades old Way-Wigner radioactive decay relationship and the inverse square law. This work uses state-of-the-art methods and better data to improve the original slide rules and also to extend the slide rule concept to three additional systems; i.e., highly enriched (93.2 wt%) uranium damp (H/{sup 235}U = 10) powder (U{sub 3}O{sub 8}) and low-enriched (5 wt%) uranium mixtures (UO{sub 2}F{sub 2}) with a H/{sup 235}U ratio of 200 and 500. Although the improved slide rules differ only slightly from the original slide rules, the improved slide rules and also the new slide rules can be used with greater confidence since they are based on more rigorous methods and better nuclear data.

The connection between recorded volumetric CT dose index (CTDI vol) and determined mean fetal dose (Df) was examined from metal-oxide-semiconductor field-effect transistor dose measurements on an anthropomorphic female phantom in four stages of pregnancy in a 64-slice CT scanner. Automated tube current modulation kept the mean Df fairly constant through all pregnancy stages in trauma (4.4-4.9 mGy) and abdomino-pelvic (2.1-2.4 mGy) protocols. In pulmonary angiography protocol, the mean Df increased exponentially as the distance from the end of the scan range decreased (0.01-0.09 mGy). For trauma protocol, the relative mean Df as a function of gestational age were in the range 0.80-0.97 compared with the mean CTDI vol. For abdomino-pelvic protocol, the relative mean Df was 0.57-0.79 and for pulmonary angiography protocol, 0.01-0.05 compared with the mean CTDI vol, respectively. In conclusion, if the fetus is in the primary beam, the CTDI vol can be used as an upper estimate of the fetal dose. If the fetus is not in the primary beam, the fetal dose can be estimated by considering also the distance of the fetus from the scan range. PMID:25836690

Empirical information on the effects of low doses of ionizing radiation is beset by severe limitations. Theoretical considerations of biophysics can guide the analysis of epidemiological data by indicating certain dose-response relations or eliminating others. Thus, it can be shown that at low doses there must be proportionality between dose and effect on non-interacting cells and that one must anticipate different dose-effect relations upon exposure to markedly different types of radiation. PMID:7336764

Calculational methods for estimation of dose from external proton exposure of arbitrary convex bodies are briefly reviewed. All the necessary information for the estimation of dose in soft tissue is presented. Special emphasis is placed on retaining the effects of nuclear reaction, especially in relation to the dose equivalent. Computer subroutines to evaluate all of the relevant functions are discussed. Nuclear reaction contributions for standard space radiations are in most cases found to be significant. Many of the existing computer programs for estimatingdose in which nuclear reaction effects are neglected can be readily converted to include nuclear reaction effects by use of the subroutines described herein.

Inconsistencies permeate the literature regarding small bowel dose tolerance limits for stereotactic body radiation therapy (SBRT) treatments. In this review, we organized these diverse published limits with MD Anderson at Cooper data into a unified framework, constructing the dose-volume histogram (DVH) Risk Map, demonstrating low-risk and high-risk SBRT dose tolerance limits for small bowel. Statistical models of clinical data from 2 institutions were used to assess the safety spectrum of doses used in the exposure of the gastrointestinal tract in SBRT; 30% of the analyzed cases had vascular endothelial growth factor inhibitors (VEGFI) or other biological agents within 2 years before or after SBRT. For every dose tolerance limit in the DVH Risk Map, the probit dose-response model was used to estimate the risk level from our clinical data. Using the current literature, 21Gy to 5cc of small bowel in 3 fractions has low toxicity and is reasonably safe, with 6.5% estimated risk of grade 3 or higher complications, per Common Terminology Criteria for Adverse Events version 4.0. In the same fractionation for the same volume, if lower risk is required, 16.2Gy has an estimated risk of only 2.5%. Other volumes and fractionations are also reviewed; for all analyzed high-risk small bowel limits, the risk is 8.2% or less, and the low-risk limits have 4% or lower estimated risk. The results support current clinical practice, with some possibility for dose escalation. PMID:27000513

This report describes approaches to calculating and expressing radiationdoses to the embryo/fetus from internal radionuclides. Information was obtained for selected, occupationally significant radioelements that provide a spectrum of metabolic and dosimetric characteristics. Evaluations are also presented for inhaled inert gases and for selected radiopharmaceuticals. Fractional placental transfer and/or ratios of concentration in the embryo/fetus to that in the woman were calculated for these materials. The ratios were integrated with data from biokinetic transfer models to estimate radioactivity levels in the embryo/fetus as a function of stage of pregnancy and time after entry into the transfer compartment or blood of the pregnant woman. These results are given as tables of deposition and retention in the embryo/fetus as a function of gestational age at exposure and elapsed time following exposure. Methodologies described by MIRD were extended to formalize and describe details for calculating radiation absorbed doses to the embryo/fetus. Calculations were performed using a model situation that assumed a single injection of 1 {mu}Ci into a woman`s blood; independent calculations were performed for administration at successive months of pregnancy. Gestational -stage-dependent dosimetric tabulations are given together with tables of correlations and relationships. Generalized surrogate dose factors and categorizations are provided in the report to provide for use in operational radiological protection situations. These approaches to calculation yield radiation absorbed doses that can be converted to dose equivalent by multiplication by quality factor. Dose equivalent is the most common quantity for stating prenatal dose limits in the United States and is appropriate for the types of effect that are usually associated with prenatal exposure. If it is desired to obtain alternatives for other purposes, this value can be multiplied by appropriate weighting factors.

The objective of this study was to identify the radiation exposure dose of patients, as well as staff caused by fluoroscopy for C-arm-assisted vascular surgical operation and to estimate carcinogenic risk due to such exposure dose. The study was conducted in 71 patients (53 men and 18 women) who had undergone vascular surgical intervention at the division of vascular surgery in the University Hospital from November of 2011 to April of 2012. It had used a mobile C-arm device and calculated the radiation exposure dose of patient (dose-area product, DAP). Effective dose was measured by attaching optically stimulated luminescence on the radiation protectors of staff who participates in the surgery to measure the radiation exposure dose of staff during the vascular surgical operation. From the study results, DAP value of patients was 308.7 Gy cm2 in average, and the maximum value was 3085 Gy cm2. When converted to the effective dose, the resulted mean was 6.2 m Gy and the maximum effective dose was 61.7 milliSievert (mSv). The effective dose of staff was 3.85 mSv; while the radiation technician was 1.04 mSv, the nurse was 1.31 mSv. All cancer incidences of operator are corresponding to 2355 persons per 100,000 persons, which deemed 1 of 42 persons is likely to have all cancer incidences. In conclusion, the vascular surgeons should keep the radiation protection for patient, staff, and all participants in the intervention in mind as supervisor of fluoroscopy while trying to understand the effects by radiation by themselves to prevent invisible danger during the intervention and to minimize the harm.

Several studies have well documented that the risk of secondary neoplasms is increasing among patients having received radiation therapy as part of their primary anticancer treatment. Most frequently, radiation-induced neoplasms occur in volume exposed to high doses. However, the impact of "low" doses (<5 Gy) in radiation-induced carcinogenesis should be clinically considered because modern techniques of intensity-modulated radiation therapy (IMRT) or stereotactic irradiation significantly increase tissue volumes receiving low doses. The risk inherent to these technologies remains uncertain and estimates closely depend on the chosen risk model. According to the (debated) linear no-threshold model, the risk of secondary neoplasms could be twice higher with IMRT, as compared to conformal radiation therapy. It seems that only proton therapy could decrease both high and low doses delivered to non-target volumes. Except for pediatric tumors, for which the unequivocal risk of second malignancies (much higher than in adults) should be taken into account, epidemiological data suggest that the risk of secondary cancer related to low doses could be very low, even negligible in some cases. However, clinical follow-up remains insufficient and a marginal increase in secondary tumors could counterbalance the benefit of a highly sophisticated irradiation technique. It therefore remains necessary to integrate the potential risk of new irradiation modalities in a risk-adapted strategy taking into account therapeutic objectives but also associated risk factors, such as age (essentially), chemotherapy, or life style. PMID:24257106

This work contains calculation data of generalized doses and dose equivalents in critical organs and tissues of cosmonauts produces by galactic cosmic rays (GCR), solar cosmic rays (SCR) and the Earth’s radiation belts (ERB) that will impact crewmembers during a flight to Mars, while staying in the landing module and on the Martian surface, and during the return to Earth. Also calculated total radiation risk values during whole life of cosmonauts after the flight are presented. Radiation risk (RR) calculations are performed on the basis of a radiobiological model of radiation damage to living organisms, while taking into account reparation processes acting during continuous long-term exposure at various dose rates and under acute recurrent radiation impact. The calculations of RR are performed for crewmembers of various ages implementing a flight to Mars over 2 - 3 years in maximum and minimum of the solar cycle. The total carcinogenic and non-carcinogenic RR and possible life-span shortening are estimated on the basis of a model of the radiation death probability for mammals. This model takes into account the decrease in compensatory reserve of an organism as well as the increase in mortality rate and descent of the subsequent lifetime of the cosmonaut. The analyzed dose distributions in the shielding and body areas are applied to making model calculations of tissue equivalent spherical and anthropomorphic phantoms.

... (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... employees at any Department of Energy (DOE) facility who were exposed to radiation but for whom it is not feasible to estimate their radiationdose, and on whether there is reasonable likelihood that...

... (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... employees at any Department of Energy facility who were exposed to radiation but for whom it is not feasible to estimate their radiationdose, and on whether there is reasonable likelihood that such...

... (SDRR), Advisory Board on Radiation and Worker Health (ABRWH or the Advisory Board), National Institute... employees at any Department of Energy facility who were exposed to radiation but for whom it is not feasible to estimate their radiationdose, and on whether there is reasonable likelihood that such...

Obviously, a single dosimeter on the chest can underestimate effective dose (E) and effective dose equivalent (HE) significantly when radiation comes from the back because the dosimeter on the chest is shielded by the body of a radiation worker. This problem can be solved by using an extra dosimeter on the back so that at least one dosimeter is always directly exposed to radiation. In this work, the use of two dosimeters was studied using the MCNP code and mathematical phantoms. First, an optimal combination of dosimeter weighting factors was found to be 0.58 and 0.42 for chest and back dosimeters, respectively, through a systematic optimization process. The optimal algorithm, which uses these weighting factors, was superior to other algorithms reported in the literature. The underestimation problem when using a single-dosimeter approach for posterior incident radiation was completely solved by using two dosimeters and the optimal algorithm. The two-dosimeter approach also estimated E and HE very well for a broad range of frontal incident photon beams, neither underestimating E or HE by more than 11%, nor overestimating by more than about 50%. Although the use of two dosimeters effectively solved the underestimation problem of the single-dosimeter approach for posterior incident radiation, this approach overestimated E and HE for lateral, overhead, and underfoot beam directions. However, this overestimation can be reduced by using suitably selected anisotropic-responding dosimeters. To study the effect of anisotropic-responding properties of personal dosimeters on the estimation of E and HE, this work considered several types of anisotropic-responding dosimeters. In practical exposure situations, radiation workers move during exposure, which results in less overestimation of E and HE than static lateral, overhead, and underfoot exposures. To quantify the reduction of the overestimation by the movement of radiation workers, we averaged photon beam results over

This report describes a tool for use by organizational management teams to plan, manage, and oversee personnel exposures within their organizations. The report encompasses personnel radiation exposures received from activities associated with the B-Cell Cleanout Project, Surveillance and Maintenance Project, the Mk-42 Project, and other minor activities. It is designed to provide verifiable Radiological Performance Reports. The primary area workers receive radiation exposure is the Radiochemical Engineering Complex airlock. Entry to the airlock is necessary for maintenance of cranes and other equipment, and to set up the rail system used to move large pieces of equipment and shipping casks into and out of the airlock. Transfers of equipment and materials from the hot cells in the complex to the airlock are required to allow dose profiles of waste containers, shuffling of waste containers to allow grouting activities to go on, and to allow maintenance of in-cell cranes. Both DOE and the Pacific Northwest Laboratory (PNL) are currently investing in state-of-the-art decontamination equipment. Challenging goals for exposure reduction were established for several broad areas of activity. Exposure estimates and goals developed from these scheduled activities will be compared against actual exposures for scheduled and unscheduled activities that contributed to exposures received by personnel throughout the year. Included in this report are life cycle exposure estimates by calendar year for the B-Cell Cleanout project, a three-year estimate of exposures associated with Surveillance and Maintenance, and known activities for Calendar Year (CY) 1995 associated with several smaller projects. These reports are intended to provide a foundation for future doseestimates, by year, requiring updating as exposure conditions change or new avenues of approach to performing work are developed.

Purpose: Many recent computed tomography (CT) dose reduction approaches belong to one of three categories: statistical reconstruction algorithms, efficient x-ray detectors, and optimized CT acquisition schemes with precise control over the x-ray distribution. The latter category could greatly benefit from fast and accurate methods for doseestimation, which would enable real-time patient-specific protocol optimization. Methods: The authors present a new method for volumetrically reconstructing absorbed dose on a per-voxel basis, directly from the actual CT images. The authors’ specific implementation combines a distance-driven pencil-beam approach to model the first-order x-ray interactions with a set of Gaussian convolution kernels to model the higher-order x-ray interactions. The authors performed a number of 3D simulation experiments comparing the proposed method to a Monte Carlo based ground truth. Results: The authors’ results indicate that the proposed approach offers a good trade-off between accuracy and computational efficiency. The images show a good qualitative correspondence to Monte Carlo estimates. Preliminary quantitative results show errors below 10%, except in bone regions, where the authors see a bigger model mismatch. The computational complexity is similar to that of a low-resolution filtered-backprojection algorithm. Conclusions: The authors present a method for analytic dose reconstruction in CT, similar to the techniques used in radiation therapy planning with megavoltage energies. Future work will include refinements of the proposed method to improve the accuracy as well as a more extensive validation study. The proposed method is not intended to replace methods that track individual x-ray photons, but the authors expect that it may prove useful in applications where real-time patient-specific doseestimation is required.

This report addresses laboratory measurement error in estimates of external doses obtained from personnel dosimeters, and investigates the effects of these errors on linear dose-response analyses of data from epidemiologic studies of nuclear workers. These errors have the distinguishing feature that they are independent across time and across workers. Although the calculations made for this report were based on Hanford data, the overall conclusions are likely to be relevant for other epidemiologic studies of workers exposed to external radiation.

Radiation treatments are often delivered to patients with brain metastases. For those patients who receive radiation to the entire brain, there is a risk of long-term neuro-cognitive side effects, which may be due to damage to the hippocampus. In clinical MRI and CT scans it can be difficult to identify the hippocampus, but once identified it can be partially spared from radiationdose. Using deformable image registration we demonstrate a semi-automatic technique for obtaining an estimated location of this structure in a clinical MRI or CT scan. Deformable image registration is a useful tool in other areas such as adaptive radiotherapy, where the radiation oncology team monitors patients during the course of treatment and adjusts the radiation treatments if necessary when the patient anatomy changes. Deformable image registration is used in this setting, but there is a considerable level of uncertainty. This work represents one of many possible approaches at investigating the nature of these uncertainties utilizing consistency metrics. We will show that metrics such as the inverse consistency error correlate with actual registration uncertainties. Specifically relating to brain metastases, this work investigates where in the brain metastases are likely to form, and how the primary cancer site is related. We will show that the cerebellum is at high risk for metastases and that non-uniform dose distributions may be advantageous when delivering prophylactic cranial irradiation for patients with small cell lung cancer in complete remission.

This report contains a system study of estimatedradiationdoses to the public and workers resulting from the transport of spent fuel from commercial nuclear power reactors to a geologic repository. The report contains a detailed breakdown of activities and a description of time/distance/dose-rate estimates for each activity within the system. Collective doses are estimated for each of the major activities at the reactor site, in transit, and at the repository receiving facility. Annual individual doses to the maximally exposed individuals or groups of individuals are also estimated. A total of 17 alternatives and subalternatives to the postulated reference transportation system are identified, conceptualized, and their dose-reduction potentials and costs estimated. Resulting ratios of ..delta..cost/..delta..collective system dose for each alternative relative to the postulated reference transportation system are given. Most of the alternatives evaluated are estimated to provide both cost and dose reductions. Major reductions in transportation system dose and cost are estimated to result from using higher-capacity rail and truck casks, and particularly when replacing legalweight truck casks with ''advanced design'' overweight truck casks. The greatest annual dose reduction to the highest exposed individual workers (i.e., at the repository) is estimated to be achieved by using remote handling equipment for the cask handling operations at the repository. Additional shielding is also effective in reducing doses to both radiation workers at the reactor and repository and to transport workers. 69 refs., 36 figs., 156 tabs.

Five algorithms producing daily solar radiation surrogates using daily temperatures and rainfall were evaluated using measured solar radiation data for seven U.S. locations. The algorithms were compared both in terms of accuracy of daily solar radiationestimates and terms of response when used in a plant growth simulation model (CERES-wheat). Requirements for accuracy of solar radiation for plant growth simulation models are discussed. One algorithm is recommended as being best suited for use in these models when neither measured nor satellite estimated solar radiation values are available.

Health risk assessments for sites contaminated with chemical warfare agents require a comparison of the potential levels of exposure with a characterization of the toxic potency of each chemical. For noncancer health effects, toxic potency is expressed in terms of Reference Doses (RfD). A RfD is a daily exposure level or dose (usually expressed in units of milligrams of chemical per kilogram body weight per day) for the human population, including sensitive subpopulations, that is likely to be without an appreciable risk of deleterious effects. A daily exposure at or below the RfD is not likely to be associated with health risks, but as the amount of chemical that an individual is exposed to increases above the RfD, the probability that an adverse effect will occur also increases. A RfD is derived by first examining the available human or animal toxicity data to identify a dose or exposure that corresponds to a no-observed-adverse-effect level (NOAEL) or a lowest-observed-adverse-effect level (LOAEL). The NOAEL is the exposure level at which there are no statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control. Effects may be produced at this level, but they are not considered to be adverse if they do not result in functional impairment or pathological lesions that affect the performance of the whole organism or which reduce an organism's ability to cope with additional challenge. The LOAEL is the lowest exposure level at which there are statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control. If only a LOAEL is identified by the toxicity data, a NOAEL is estimated by dividing the LOAEL by a factor no greater than 10. This extrapolation factor of 10 or less is termed the LOAEL-to-NOAEL Uncertainty Factor (UFL). The NOAEL is also adjusted by the application of other

We have coupled our dose calculation tool Pandemonium with a discrete-event, object-oriented, process-modeling system ProMosO to analyze a set of alternatives for plutonium purification operations. The results follow expected trends and indicate, from a dose perspective, that an experimental flowsheet may warrant further research to see if it can be scaled to industrial levels. Flowsheets that include fluoride processes resulted in the largest doses.

Recent investigations have shown that nuclear magnetic resonance (NMR) can be used in conjunction with a suitable chemical dosimeter to estimate the dose from ionizing radiation (Gore et al., Phys Med. Biol. 29, 1189-1197, 1984). Based on this fact it was proposed that spatial dose distributions can be measured in gels infused with the chemical dosimeter using NMR imaging. There have been few such attempts and they provided only qualitative results. In this paper, we report results demonstrating the feasibility of obtaining quantitative dose distribution measurements by this technique. It is shown that quantitative dose distribution measurements necessitate the calculation of relaxation rate maps. We have determined that the spin-spin relaxation rate is a more sensitive parameter than the spin-lattice relaxation rate. It is also demonstrated that the addition of chemical sensitizers could improve the dose sensitivity of the measured NMR parameters. The two features characterizing a photon beam, depth-dose relationship, and beam profile as measured by this technique are in good agreement with the measurements using conventional methods, ionization chambers, and film dosimetry. PMID:1924718

Because of its advantageous depth-dose relationship, proton radiotherapy is an emerging treatment modality for patients with liver cancer. Although the proton dose distribution conforms to the target, healthy tissues throughout the body receive low doses of stray radiation, particularly neutrons that originate in the treatment unit or in the patient. The aim of this study was to calculate the effective dose from stray radiation and estimate the corresponding risk of second cancer fatality for a patient receiving proton beam therapy for liver cancer. Effective dose from stray radiation was calculated using detailed Monte Carlo simulations of a double-scattering proton therapy treatment unit and a voxelized human phantom. The treatment plan and phantom were based on CT images of an actual adult patient diagnosed with primary hepatocellular carcinoma. For a prescribed dose of 60 Gy to the clinical target volume, the effective dose from stray radiation was 370 mSv; 61% of this dose was from neutrons originating outside of the patient while the remaining 39% was from neutrons originating within the patient. The excess lifetime risk of fatal second cancer corresponding to the total effective dose from stray radiation was 1.2%. The results of this study establish a baseline estimate of the stray radiationdose and corresponding risk for an adult patient undergoing proton radiotherapy for liver cancer and provide new evidence to corroborate the suitability of proton beam therapy for the treatment of liver tumors.

Because of its advantageous depth-dose relationship, proton radiotherapy is an emerging treatment modality for patients with liver cancer. Although the proton dose distribution conforms to the target, healthy tissues throughout the body receive low doses of stray radiation, particularly neutrons that originate in the treatment unit or in the patient. The aim of this study was to calculate the effective dose from stray radiation and estimate the corresponding risk of second cancer fatality for a patient receiving proton beam therapy for liver cancer. Effective dose from stray radiation was calculated using detailed Monte Carlo simulations of a double-scattering proton therapy treatment unit and a voxelized human phantom. The treatment plan and phantom were based on CT images of an actual adult patient diagnosed with primary hepatocellular carcinoma. For a prescribed dose of 60 Gy to the clinical target volume, the effective dose from stray radiation was 370 mSv; 61% of this dose was from neutrons originating outside of the patient while the remaining 39% was from neutrons originating within the patient. The excess lifetime risk of fatal second cancer corresponding to the total effective dose from stray radiation was 1.2%. The results of this study establish a baseline estimate of the stray radiationdose and corresponding risk for an adult patient undergoing proton radiotherapy for liver cancer and provide new evidence to corroborate the suitability of proton beam therapy for the treatment of liver tumors.

The Fukushima Health Management Survey (including the Basic Survey for external doseestimation and four detailed surveys) was launched after the Fukushima Dai-ichi Nuclear Power Plant accident. The Basic Survey consists of a questionnaire that asks Fukushima Prefecture residents about their behavior in the first four months after the accident; and responses to the questionnaire have been returned from many residents. The individual external doses are estimated by using digitized behavior data and a computer program that included daily gamma ray dose rate maps drawn after the accident. The individual external doses of 421,394 residents for the first four months (excluding radiation workers) had a distribution as follows: 62.0%, <1 mSv; 94.0%, <2 mSv; 99.4%, <3 mSv. The arithmetic mean and maximum for the individual external doses were 0.8 and 25 mSv, respectively. While most doseestimation studies were based on typical scenarios of evacuation and time spent inside/outside, the Basic Survey estimateddoses considering individually different personal behaviors. Thus, doses for some individuals who did not follow typical scenarios could be revealed. Even considering such extreme cases, the estimated external doses were generally low and no discernible increased incidence of radiation-related health effects is expected. PMID:26239643

The Fukushima Health Management Survey (including the Basic Survey for external doseestimation and four detailed surveys) was launched after the Fukushima Dai-ichi Nuclear Power Plant accident. The Basic Survey consists of a questionnaire that asks Fukushima Prefecture residents about their behavior in the first four months after the accident; and responses to the questionnaire have been returned from many residents. The individual external doses are estimated by using digitized behavior data and a computer program that included daily gamma ray dose rate maps drawn after the accident. The individual external doses of 421,394 residents for the first four months (excluding radiation workers) had a distribution as follows: 62.0%, <1 mSv; 94.0%, <2 mSv; 99.4%, <3 mSv. The arithmetic mean and maximum for the individual external doses were 0.8 and 25 mSv, respectively. While most doseestimation studies were based on typical scenarios of evacuation and time spent inside/outside, the Basic Survey estimateddoses considering individually different personal behaviors. Thus, doses for some individuals who did not follow typical scenarios could be revealed. Even considering such extreme cases, the estimated external doses were generally low and no discernible increased incidence of radiation-related health effects is expected. PMID:26239643

The Fukushima Health Management Survey (including the Basic Survey for external doseestimation and four detailed surveys) was launched after the Fukushima Dai-ichi Nuclear Power Plant accident. The Basic Survey consists of a questionnaire that asks Fukushima Prefecture residents about their behavior in the first four months after the accident; and responses to the questionnaire have been returned from many residents. The individual external doses are estimated by using digitized behavior data and a computer program that included daily gamma ray dose rate maps drawn after the accident. The individual external doses of 421,394 residents for the first four months (excluding radiation workers) had a distribution as follows: 62.0%, <1 mSv 94.0%, <2 mSv 99.4%, <3 mSv. The arithmetic mean and maximum for the individual external doses were 0.8 and 25 mSv, respectively. While most doseestimation studies were based on typical scenarios of evacuation and time spent inside/outside, the Basic Survey estimateddoses considering individually different personal behaviors. Thus, doses for some individuals who did not follow typical scenarios could be revealed. Even considering such extreme cases, the estimated external doses were generally low and no discernible increased incidence of radiation-related health effects is expected.

The purpose of this work is to provide an evaluation of the mean glandular dose (MGD) for breast computed tomography (CT) with synchrotron radiation in an axial scanning configuration with a partial or total organ volume irradiation, for the in vivo program of breast CT ongoing at the ELETTRA facility (Trieste, Italy). A Geant4 Monte Carlo code was implemented, simulating the photon irradiation from a synchrotron radiation source in the energetic range from 8 to 50 keV with 1 keV intervals, to evaluate the MGD. The code was validated with literature data, in terms of mammographic normalized glandular dose coefficients (DgN) and with ad hoc experimental data, in terms of computed tomography dose index (CTDI). Simulated cylindrical phantoms of different sizes (diameter at phantom base 8, 10, 12, 14 or 16 cm, axial length 1.5 times the radius) and glandular fraction by weight (0%, 14.3%, 25%, 50%, 75% and 100%) were implemented into the code. The validation of the code shows an excellent agreement both with previously published work and in terms of DgN and CDTI measurements. The implemented simulations show a dependence of the glandular doseestimate on the vertical dimension of the irradiated zone when a partial organ irradiation was implemented. Specific normalized coefficients for calculating the MGD to the whole breast or to the single irradiated slice were reported. PMID:26683710

The purpose of this work is to provide an evaluation of the mean glandular dose (MGD) for breast computed tomography (CT) with synchrotron radiation in an axial scanning configuration with a partial or total organ volume irradiation, for the in vivo program of breast CT ongoing at the ELETTRA facility (Trieste, Italy). A Geant4 Monte Carlo code was implemented, simulating the photon irradiation from a synchrotron radiation source in the energetic range from 8 to 50 keV with 1 keV intervals, to evaluate the MGD. The code was validated with literature data, in terms of mammographic normalized glandular dose coefficients (DgN) and with ad hoc experimental data, in terms of computed tomography dose index (CTDI). Simulated cylindrical phantoms of different sizes (diameter at phantom base 8, 10, 12, 14 or 16 cm, axial length 1.5 times the radius) and glandular fraction by weight (0%, 14.3%, 25%, 50%, 75% and 100%) were implemented into the code. The validation of the code shows an excellent agreement both with previously published work and in terms of DgN and CDTI measurements. The implemented simulations show a dependence of the glandular doseestimate on the vertical dimension of the irradiated zone when a partial organ irradiation was implemented. Specific normalized coefficients for calculating the MGD to the whole breast or to the single irradiated slice were reported.

The thyroid gland is highly sensitive to the carcinogenic effects of ionizing radiation. Previously, we reported a significant increase of thyroid cancer and adenomas among 10,834 persons in Israel who received radiotherapy to the scalp for ringworm. These findings have now been extended with further follow-up and revised dosimetry. Overall, 98 thyroid tumors were identified among the exposed and 57 among 10,834 nonexposed matched population and 5392 sibling comparison subjects. An estimated thyroid dose of 9 cGy was linked to a fourfold (95% Cl = 2.3-7.9) increase of malignant tumors and a twofold (95% Cl = 1.3-3.0) increase of benign tumors. The dose-response relationship was consistent with linearity. Age was an important modifier of risk with those exposed under 5 years being significantly more prone to develop thyroid tumors than older children. The pattern of radiation risk over time could be described on the basis of a constant multiplication of the background rate, and an absolute risk model was not compatible with the observed data. Overall, the excess relative risk per cGy for thyroid cancer development after childhood exposure is estimated as 0.3, and the absolute excess risk as 13 per 10(6) PY-cGy. For benign tumors the estimated excess relative risk was 0.1 per cGy and the absolute risk was 15 per 10(6) PY-cGy.

Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiationdose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiationdose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

The objectives of this project are to quantify the dose reduction effect provided by a lead shield for patients with cardiac implantable electronic devices (CIED) during a clinically realistic radiation treatment on phantom and to provide a simple model of doseestimation to predict dose received by CIED in a wide range of situations. The shield used in this project is composed of a lead sheet wrapped in thermoplastic. Dose measurements were made with a plastic scintillation detector (PSD). The phantom was treated with ten different plans. Three of these cases were treated with intensity-modulated radiation therapy (IMRT) and the others received standard 3D conformal radiation therapy (3D CRT). Lateral dose measurement for photon fields was made to establish a dose prediction model. On average, the use of the lead shield reduced the dose to CIEDs by 19% ± 13%. Dose reduction was most important for breast cases, with a mean reduction of 31% ± 15%. In three cases, the total dose reduction was more than 25 cGy over the complete treatment. For the three IMRT cases, the mean dose reduction was 11% ± 9%. On average, the difference between the TPS prediction and the measurement was 71%, while it was only 14% for the dose prediction model. It was demonstrated that a lead shield can be efficiently used for reducing doses to CIED with a wide range of clinical plans. In patients treated with IMRT modality treatment, the shielding should be used only for those with more than two anterior fields over seven fields. In the case of 3D CRT patients, the shielding should be used for those with a dose on the CIED higher than 50 cGy and with a reduction of dose higher than 10 cGy. The dose prediction model developed in this study can be an easy way to have a better estimation of the out-of-field dose than the TPS. PMID:26699550

The importance of knowing the patient actual position is essential for intensity modulated radiation therapy (IMRT). This procedure uses tightened margin and escalated tumor dose. In order to eliminate the uncertainty of the geometry in IMRT, daily imaging is prefered. The imaging dose, limited field of view and the imaging concurrency of the MVCT (mega-voltage computerized tomography) are investigated in this work. By applying partial volume imaging (PVI), imaging dose can be reduced for a region of interest (ROI) imaging. The imaging dose and the image quality are quantitatively balanced with inverse imaging dose planning. With PVI, 72% average imaging dose reduction was observed on a typical prostate patient case. The algebraic reconstruction technique (ART) based projection onto convex sets (POCS) shows higher robustness than filtered back projection when available imaging data is not complete and continuous. However, when the projection is continuous as in the actual delivery, a non-iterative wavelet based multiresolution local tomography (WMLT) is able to achieve 1% accuracy within the ROI. The reduction of imaging dose is dependent on the size of ROI. The improvement of concurrency is also discussed based on the combination of PVI and WMLT. Useful target images were acquired with treatment beams and the temporal resolution can be increased to 20 seconds in tomotherapy. The data truncation problem with the portal imager was also studied. Results show that the image quality is not adversely affected by truncation when WMLT is employed. When the online imaging is available, a perturbation dose calculation (PDC) that estimates the actual delivered dose is proposed. Corrected from the Fano's theorem, PDC counts the first order term in the density variation to calculate the internal and external anatomy change. Although change in the dose distribution that is caused by the internal organ motion is less than 1% for 6 MV beams, the external anatomy change has

A systematic radiological survey has been carried out in the region of high-background radiation area in Kollam district of Kerala to define the natural gamma-radiation levels. One hundred and forty seven soil samples from high-background radiation areas and five samples from normal background region were collected as per standard sampling procedures and were analysed for (238)U, (232)Th and (40)K by gamma-ray spectroscopy. External gamma dose rates at all sampling locations were also measured using a survey meter. The activities of (238)U, (232)Th and (40)K was found to vary from 17 to 3081 Bq kg(-1), 54 to 11976 Bq kg(-1) and BDL (67.4 Bq kg(-1)) to 216 Bq kg(-1), respectively, in the study area. Such heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of beach sand soil in the region. Radium equivalent activities were found high in several locations. External gamma dose rates estimated from the levels of radionuclides in soil had a range from 49 to 9244 nGy h(-1). The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples. PMID:21515614

The International Space Station (ISS) is now a reality with the start of a permanent human presence on board. Radiation presents a serious risk to the health and safety of the astronauts, and there is a clear requirement for estimating their exposures prior to and after flights. Predictions of the dose rate at times other than solar minimum or solar maximum have not been possible, because there has been no method to calculate the trapped-particle spectrum at intermediate times. Over the last few years, a tissue-equivalent proportional counter (TEPC) has been flown at a fixed mid-deck location on board the Space Shuttle in 51.65 degrees inclination flights. These flights have provided data that cover the expected changes in the dose rates due to changes in altitude and changes in solar activity from the solar minimum to the solar maximum of the current 23rd solar cycle. Based on these data, a simple function of the solar deceleration potential has been derived that can be used to predict the galactic cosmic radiation (GCR) dose rates to within +/-10%. For altitudes to be covered by the ISS, the dose rate due to the trapped particles is found to be a power-law function, rho(-2/3), of the atmospheric density, rho. This relationship can be used to predict trapped dose rates inside these spacecraft to +/-10% throughout the solar cycle. Thus, given the shielding distribution for a location inside the Space Shuttle or inside an ISS module, this approach can be used to predict the combined GCR + trapped dose rate to better than +/-15% for quiet solar conditions. PMID:11754644

The International Space Station (ISS) is now a reality with the start of a permanent human presence on board. Radiation presents a serious risk to the health and safety of the astronauts, and there is a clear requirement for estimating their exposures prior to and after flights. Predictions of the dose rate at times other than solar minimum or solar maximum have not been possible, because there has been no method to calculate the trapped-particle spectrum at intermediate times. Over the last few years, a tissue-equivalent proportional counter (TEPC) has been flown at a fixed mid-deck location on board the Space Shuttle in 51.65 degrees inclination flights. These flights have provided data that cover the expected changes in the dose rates due to changes in altitude and changes in solar activity from the solar minimum to the solar maximum of the current 23rd solar cycle. Based on these data, a simple function of the solar deceleration potential has been derived that can be used to predict the galactic cosmic radiation (GCR) dose rates to within +/-10%. For altitudes to be covered by the ISS, the dose rate due to the trapped particles is found to be a power-law function, rho(-2/3), of the atmospheric density, rho. This relationship can be used to predict trapped dose rates inside these spacecraft to +/-10% throughout the solar cycle. Thus, given the shielding distribution for a location inside the Space Shuttle or inside an ISS module, this approach can be used to predict the combined GCR + trapped dose rate to better than +/-15% for quiet solar conditions.

This paper summarizes individual and collective doseestimates for the internal organs of hypothetical yet representative residents of selected communities that received measurable fallout from nuclear detonations at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated with over 20 radionuclides, were estimated with use of the PATHWAY food-chain-transport model to provide estimates of central tendency and uncertainty. The thyroid gland received much higher doses than other internal organs and tissues. In a avery few cases, infants might have received thyroid doses in excess of 1 Gy, depending on location, diet, and timing of fallout. {sup 131}I was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (<3%) than those from external gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallout events; doses to more distantly located people were generally smaller, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal organ doses through ingestion varied dramatically with seasonal timing of the test, with maximum dose per unit fallout occurring for early summer depositions when milk cows were on pasture and fresh, local vegetables were used. Within specific communities, internal doses differed by age, sex, and lifestyle. Collective internal doseestimates for specific geographic areas are provided.

This paper summarizes individual and collective doseestimates for the internal organs of hypothetical yet representative residents of selected communities that received measurable fallout from nuclear detonations at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated with over 20 radionuclides, were estimated with use of the PATHWAY food-chain-transport model to provide estimates of central tendency and uncertainty. The thyroid gland received much higher doses than other internal organs and tissues. In a very few cases, infants might have received thyroid doses in excess of 1 Gy, depending on location, diet, and timing of fallout. 131I was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (< 3%) than those from external gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallout events; doses to more distantly located people were generally smaller, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal organ doses through ingestion varied dramatically with seasonal timing of the test, with maximum dose per unit fallout occurring for early summer depositions when milk cows were on pasture and fresh, local vegetables were used. Within specific communities, internal doses differed by age, sex, and lifestyle. Collective internal doseestimates for specific geographic areas are provided. PMID:8830749

The author puts low dose irradiation risks in perspective using average background radiationdoses for standards. He assailed irresponsible media coverage during the height of public interest in the Three-Mile Island Reactor incident. (PCS)

Persons traveling in space can accumulate fairly large doses of radiation, up to several Sv, at low-to-moderate dose rates. In general these dose rates are low enough so that deterministic effects can be avoided, although shielding may be necessary. An important question, however, is the stochastic effects (induction of cancer and genetic defects) of these doses. Most radiation-risk estimates are based on dose reconstruction and epidemiologic follow-up of the survivors of the atomic bombings on Japan, events that delivered doses nearly instantaneously. It has been hoped that stochastic effects would be less probable for radiation delivered at lower dose rates, but few opportunities have been available to examine this question in humans. The Mayak Production Association (MPA) was the first Russian site for the production and separation of plutonium. This plant began operation in 1948, and during its early days there were high occupational doses as well as technological failures that resulted in the release of large amounts of waste (about 10^17 Bq of liquid wastes) into the rather small Techa River. Residents along the Techa River were exposed to external radiation, and they ingested foods contaminated with 90Sr and other radionuclides. The?Techa River Cohort? has been studied for several years by scientists from the Urals Research Center for Radiation Medicine (URCRM). The purpose of the project considered here is to improve the dose-reconstruction system for the Techa River Cohort that has been under development for many years by Russian scientists at the URCRM. This, and the companion epidemiologic studies, are deemed to be unique and important, as members of the Techa River Cohort received red bone marrow doses of up to 3 Gy, but at low-to-moderate-dose rates. An increase in leukemia and cancer mortality has already been noted for this population, and further study should allow the evaluation of dose-rate-reduction factors for this situation.

The results of several major epidemiology studies on populations with particular exposure to ionizing radiation should become available during the first years of the 21(st) century. These studies are expected to provide answers to a number of questions concerning public health and radiation protection. Most of the populations concerned were accidentally exposed to radiation in ex-USSR or elsewhere or in a nuclear industrial context. The results will complete and test information on risk coming from studies among survivors of the Hiroshima and Nagasaki atomic bombs, particularly studies on the effects of low dose exposure and prolonged low-dose exposure, of different types of radiation, and environmental and host-related factors which could modify the risk of radiation-induced effects. These studies are thus important to assess the currently accepted scientific evidence on radiation protection for workers and the general population. In addition, supplementary information on radiation protection could be provided by formal comparisons and analyses combining data from populations with different types of exposure. Finally, in order to provide pertinent information for public health and radiation protection, future epidemiology studies should be targeted and designed to answer specific questions, concerning, for example, the risk for specific populations (children, patients, people with genetic predisposition). An integrated approach, combining epidemiology and studies on the mechanisms of radiation induction should provide particularly pertinent information. PMID:11938114

This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiationdose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiationdose based on the Technical Steering Panel dose decision level.

This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiationdose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiationdose based on the Technical Steering Panel dose decision level.

Astronauts in flight are exposed by the space radiation, which is mainly composed of proton, electron, heavy ion, and neutron. To assess the radiation risk, measurement and assessment of radiationdose of astronauts is indispensable. Especially, measurement for heavy ion radiation is most important as it contributes the major dose. Until now, most of the measurements and assessments of radiationdose of astronauts are based on the LET (Linear Energy Transfer) spectrum of space radiation. However, according to the ICRP Publication 123, energy and charge number of heavy ions should be measured in order to assess space radiation exposure to astronauts. In addition, from the publication, quality factors for each organs or tissues of astronauts are different and they should be calculated or measured independently. Here, a method to measure the energy and charge number of heavy ion and a voxel phantom based on the anatomy of Chinese adult male are presented for radiationdose assessment of astronauts.

This study examines results of analyses performed with the Source Term Code Package to develop updated source terms using NUREG-0956 methods. The updated source terms are to be used to assess the adequacy of current regulatory source terms used as the basis for equipment qualification. Time-dependent locational distributions of radionuclides within a containment following a severe accident have been developed. The Surry reactor has been selected in this study as representative of PWR containment designs. Similarly, the Peach Bottom reactor has been used to examine radionuclide distributions in boiling water reactors. The time-dependent inventory of each key radionuclide is provided in terms of its activity in curies. The data are to be used by Sandia National Laboratories to perform shielding analyses to estimateradiationdose to equipment in each containment design. See NUREG/CR-5175, Beta and Gamma Dose Calculations for PWR and BWR Containments.'' 6 refs., 11 tabs.

We propose a mathematical model for estimating biological damage caused by low-dose irradiation. We understand that the linear non threshold (LNT) hypothesis is realized only in the case of no recovery effects. In order to treat the realistic living objects, our model takes into account various types of recovery as well as proliferation mechanism, which may change the resultant damage, especially for the case of lower dose rate irradiation. It turns out that the lower the radiationdose rate, the safer the irradiated system of living object (which is called symbolically ``tissue'' hereafter) can have chances to survive, which can reproduce the so-called dose and dose-rate effectiveness factor (DDREF).

The complexities of the interactions between long- and short-wave radiation fluxes and the human body make it inherently difficult to estimate precisely the total radiation absorbed (R) by a human in an outdoor environment. The purpose of this project was to assess and compare three methods to estimate the radiation absorbed by a human in an outdoor environment, and to compare the impact of applying various skin and clothing albedos (alpha ( h )) on R. Field tests were conducted under both clear and overcast skies to evaluate the performance of applying a cylindrical radiation thermometer (CRT), net radiometer, and a theoretical estimation model to predict R. Three albedos were evaluated: light (alpha ( h ) = 0.57), medium (alpha ( h ) = 0.37), and dark (alpha ( h ) = 0.21). During the sampling periods, the range of error between the methods used to estimate the radiation absorbed by a cylindrical body under clear and overcast skies ranged from 3 to 8%. Clothing and skin albedo had a substantial impact on R, with the mean change in R between the darkest and lightest albedos ranging from 115 to 157 W m( - 2) over the sampling period. Radiation is one of the most important variables to consider in outdoor thermal comfort research, as R is often the largest contributor to the human energy balance equation. The methods outlined and assessed in this study can be conveniently applied to provide reliable estimates of the radiation absorbed by a human in an outdoor environment. PMID:18273649

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small. PMID:24778349

In radiation therapy, high energy photon and proton beams cause the production of secondary neutrons. This leads to an unwanted dose contribution, which can be considerable for tissues outside of the target volume regarding the long term health of cancer patients. Due to the high biological effectiveness of neutrons in regards to cancer induction, small neutron doses can be important. This study quantified the neutron doses for different radiation therapy modalities. Most of the reports in the literature used neutron dose measurements free in air or on the surface of phantoms to estimate the amount of neutron dose to the patient. In this study, dose measurements were performed in terms of neutron dose equivalent inside an anthropomorphic phantom. The neutron dose equivalent was determined using track etch detectors as a function of the distance to the isocenter, as well as for radiation sensitive organs. The dose distributions were compared with respect to treatment techniques (3D-conformal, volumetric modulated arc therapy and intensity-modulated radiation therapy for photons; spot scanning and passive scattering for protons), therapy machines (Varian, Elekta and Siemens linear accelerators) and radiation quality (photons and protons). The neutron dose equivalent varied between 0.002 and 3 mSv per treatment gray over all measurements. Only small differences were found when comparing treatment techniques, but substantial differences were observed between the linear accelerator models. The neutron dose equivalent for proton therapy was higher than for photons in general and in particular for double-scattered protons. The overall neutron dose equivalent measured in this study was an order of magnitude lower than the stray dose of a treatment using 6 MV photons, suggesting that the contribution of the secondary neutron dose equivalent to the integral dose of a radiotherapy patient is small.

The annual exposure to indoor radon, thoron and their progeny imparts a major contribution to inhalation doses received by the public. In this study, we report results of time integrated passive measurements of indoor radon, thoron and their progeny concentrations that were carried out in Garhwal Himalaya with the aim of investigating significant health risk to the dwellers in the region. The measurements were performed using recently developed LR-115 detector based techniques. The experimentally determined values of radon, thoron and their progeny concentrations were used to estimate total annual inhalation dose and annual effective doses. The equilibrium factors for radon and thoron were also determined from the observed data. The estimated value of total annual inhalation dose was found to be 1.8 ± 0.7 mSv/y. The estimated values of the annual effective dose were found to be 1.2 ± 0.5 mSv/y and 0.5 ± 0.3 mSv/y, respectively. The estimated values of radiationdoses suggest no important health risk due to exposure of radon, thoron and progeny in the study area. The contribution of indoor thoron and its progeny to total inhalation dose ranges between 13-52% with mean value of 30%. Thus thoron cannot be neglected when assessing radiationdoses. PMID:27499492

The annual exposure to indoor radon, thoron and their progeny imparts a major contribution to inhalation doses received by the public. In this study, we report results of time integrated passive measurements of indoor radon, thoron and their progeny concentrations that were carried out in Garhwal Himalaya with the aim of investigating significant health risk to the dwellers in the region. The measurements were performed using recently developed LR-115 detector based techniques. The experimentally determined values of radon, thoron and their progeny concentrations were used to estimate total annual inhalation dose and annual effective doses. The equilibrium factors for radon and thoron were also determined from the observed data. The estimated value of total annual inhalation dose was found to be 1.8 ± 0.7 mSv/y. The estimated values of the annual effective dose were found to be 1.2 ± 0.5 mSv/y and 0.5 ± 0.3 mSv/y, respectively. The estimated values of radiationdoses suggest no important health risk due to exposure of radon, thoron and progeny in the study area. The contribution of indoor thoron and its progeny to total inhalation dose ranges between 13–52% with mean value of 30%. Thus thoron cannot be neglected when assessing radiationdoses. PMID:27499492

The annual exposure to indoor radon, thoron and their progeny imparts a major contribution to inhalation doses received by the public. In this study, we report results of time integrated passive measurements of indoor radon, thoron and their progeny concentrations that were carried out in Garhwal Himalaya with the aim of investigating significant health risk to the dwellers in the region. The measurements were performed using recently developed LR-115 detector based techniques. The experimentally determined values of radon, thoron and their progeny concentrations were used to estimate total annual inhalation dose and annual effective doses. The equilibrium factors for radon and thoron were also determined from the observed data. The estimated value of total annual inhalation dose was found to be 1.8 ± 0.7 mSv/y. The estimated values of the annual effective dose were found to be 1.2 ± 0.5 mSv/y and 0.5 ± 0.3 mSv/y, respectively. The estimated values of radiationdoses suggest no important health risk due to exposure of radon, thoron and progeny in the study area. The contribution of indoor thoron and its progeny to total inhalation dose ranges between 13–52% with mean value of 30%. Thus thoron cannot be neglected when assessing radiationdoses.

Computed tomography (CT) is a powerful tool for the accurate and effective diagnosis and treatment of a variety of conditions because it allows high-resolution three-dimensional images to be acquired very quickly. However as the number of CT procedures performed globally have continued to increase; with growing concerns about patient protection. Currently, no system is in place to track patient doses and the lifetime cumulative dose from medical sources. The widespread use of CT even in developing countries has raised questions regarding the possible threat to public health especially in children. The best available risk estimates suggest that paediatric CT will result in significantly increased lifetime radiation risk over adult CT. Studies have shown that lower milliampere-second (mAs) settings can be used for children without significant loss of information. Although the risk–benefit balance is still strongly tilted toward benefit, there is still need for caution. Furthermore since the frequency of paediatric CT examinations is rapidly increasing, and estimates suggest that quantitative lifetime radiation risks for children are not negligible, efforts should be made toward more active reduction of CT exposure settings in paediatric patients. This article hopes to address this concerns and draw attention to the fact that children are not ‘small adults ’ and should therefore be treated differently. PMID:25161479

The effects of chronic low-doseradiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-doseradiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiationdose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-doseradiation.

The effects of chronic low-doseradiation on human health have not been well established. Recent studies have revealed that neural progenitor cells are present not only in the fetal brain but also in the adult brain. Since immature cells are generally more radiosensitive, here we investigated the effects of chronic low-doseradiation on cultured human neural progenitor cells (hNPCs) derived from embryonic stem cells. Radiation at low doses of 31, 124 and 496 mGy per 72 h was administered to hNPCs. The effects were estimated by gene expression profiling with microarray analysis as well as morphological analysis. Gene expression was dose-dependently changed by radiation. By thirty-one mGy of radiation, inflammatory pathways involving interferon signaling and cell junctions were altered. DNA repair and cell adhesion molecules were affected by 124 mGy of radiation while DNA synthesis, apoptosis, metabolism, and neural differentiation were all affected by 496 mGy of radiation. These in vitro results suggest that 496 mGy radiation affects the development of neuronal progenitor cells while altered gene expression was observed at a radiationdose lower than 100 mGy. This study would contribute to the elucidation of the clinical and subclinical phenotypes of impaired neuronal development induced by chronic low-doseradiation. PMID:26795421

Radiation damage is an important resolution limiting factor both in macromolecular X-ray crystallography and cryo-electron microscopy. Systematic studies in macromolecular X-ray crystallography greatly benefited from the use of dose, expressed as energy deposited per mass unit, which is derived from parameters including incident flux, beam energy, beam size, sample composition and sample size. In here, the use of dose is reintroduced for electron microscopy, accounting for the electron energy, incident flux and measured sample thickness and composition. Knowledge of the amount of energy deposited allowed us to compare doses with experimental limits in macromolecular X-ray crystallography, to obtain an upper estimate of radical concentrations that build up in the vitreous sample, and to translate heat-transfer simulations carried out for macromolecular X-ray crystallography to cryo-electron microscopy. Stroboscopic exposure series of 50-250 images were collected for different incident flux densities and integration times from Lumbricus terrestris extracellular hemoglobin. The images within each series were computationally aligned and analyzed with similarity metrics such as Fourier ring correlation, Fourier ring phase residual and figure of merit. Prior to gas bubble formation, the images become linearly brighter with dose, at a rate of approximately 0.1% per 10 MGy. The gradual decomposition of a vitrified hemoglobin sample could be visualized at a series of doses up to 5500 MGy, by which dose the sample was sublimed. Comparison of equal-dose series collected with different incident flux densities showed a dose-rate effect favoring lower flux densities. Heat simulations predict that sample heating will only become an issue for very large dose rates (50 e(-)Å(-2) s(-1) or higher) combined with poor thermal contact between the grid and cryo-holder. Secondary radiolytic effects are likely to play a role in dose-rate effects. Stroboscopic data collection combined with

Radiation damage is an important resolution limiting factor both in macromolecular X-ray crystallography and cryo-electron microscopy. Systematic studies in macromolecular X-ray crystallography greatly benefited from the use of dose, expressed as energy deposited per mass unit, which is derived from parameters including incident flux, beam energy, beam size, sample composition and sample size. In here, the use of dose is reintroduced for electron microscopy, accounting for the electron energy, incident flux and measured sample thickness and composition. Knowledge of the amount of energy deposited allowed us to compare doses with experimental limits in macromolecular X-ray crystallography, to obtain an upper estimate of radical concentrations that build up in the vitreous sample, and to translate heat-transfer simulations carried out for macromolecular X-ray crystallography to cryo-electron microscopy. Stroboscopic exposure series of 50–250 images were collected for different incident flux densities and integration times from Lumbricus terrestris extracellular hemoglobin. The images within each series were computationally aligned and analyzed with similarity metrics such as Fourier ring correlation, Fourier ring phase residual and figure of merit. Prior to gas bubble formation, the images become linearly brighter with dose, at a rate of approximately 0.1% per 10 MGy. The gradual decomposition of a vitrified hemoglobin sample could be visualized at a series of doses up to 5500 MGy, by which dose the sample was sublimed. Comparison of equal-dose series collected with different incident flux densities showed a dose-rate effect favoring lower flux densities. Heat simulations predict that sample heating will only become an issue for very large dose rates (50 e−Å−2 s−1 or higher) combined with poor thermal contact between the grid and cryo-holder. Secondary radiolytic effects are likely to play a role in dose-rate effects. Stroboscopic data collection

Since 1957, evaluations of offsite impacts from each year of operation have been summarized in publicly available, annual environmental reports. These evaluations included estimates of potential radiation exposure to members of the public, either in terms of percentages of the then permissible limits or in terms of radiationdose. The estimated potential radiationdoses to maximally exposed individuals from each year of Hanford operations are summarized in a series of tables and figures. The applicable standard for radiationdose to an individual for whom the maximum exposure was estimated is also shown. Although the estimates address potential radiationdoses to the public from each year of operations at Hanford between 1957 and 1984, their sum will not produce an accurate estimate of doses accumulated over this time period. The estimates were the best evaluations available at the time to assess potential dose from the current year of operation as well as from any radionuclides still present in the environment from previous years of operation. There was a constant striving for improved evaluation of the potential radiationdoses received by members of the public, and as a result the methods and assumptions used to estimatedoses were periodically modified to add new pathways of exposure and to increase the accuracy of the dose calculations. Three conclusions were reached from this review: radiationdoses reported for the years 1957 through 1984 for the maximum individual did not exceed the applicable dose standards; radiationdoses reported over the past 27 years are not additive because of the changing and inconsistent methods used; and results from environmental monitoring and the associated dose calculations reported over the 27 years from 1957 through 1984 do not suggest a significant dose contribution from the buildup in the environment of radioactive materials associated with Hanford operations.

It is crucial to integrate health physics into the medical management of radiation illness or injury. The key to early medical management is not necessarily radiationdose calculation and assignment, but radiationdose magnitude estimation. The magnitude of the dose can be used to predict potential biological consequences and the corresponding need for medical intervention. It is, therefore, imperative that physicians and health physicists have the necessary tools to help guide this decision making process. All internal radiationdoses should be assigned using proper dosimetry techniques, but the formal internal dosimetry process often takes time that may delay treatment, thus reducing the efficacy of some medical countermeasures. Magnitudes of inhalation or ingestion intakes or intakes associated with contaminated wounds can be estimated by applying simple rules of thumb to sample results or direct measurements and comparing the outcome to known limits for a projection of dose magnitude. Although a United States regulatory unit, the annual limit on intake (ALI) is based on committed dose, and can therefore be used as a comparison point. For example, internal dose magnitudes associated with contaminated wounds can be estimated by comparing a direct wound measurement taken soon after the injury to the product of the ingestion ALI and the associated f1 value (the fractional uptake from the small intestine to the blood). International Commission on Radiation Protection Publication 96, as well as other resources, recommends treatment based on ALI determination. Often, treatment decisions have to be made with limited information. However, one can still perform dose magnitude estimations in order to help effectively guide the need for medical treatment by properly assessing the situation and appropriately applying basic rules of thumb. PMID:20445387

Effective dose of a skeletal survey in infants using digital radiography was estimated to be 0.2 mSv using Monte Carlo simulation. Radiation risk from this procedure is, therefore, low. Radiation concern should not be an overriding factor when deciding whether skeletal survey is needed in cases of possible physical abuse. PMID:26831745

Conventional nuclear medicine dosimetry involves specifying individual organ doses. The difficulties that can arise with this approach to radiation dosimetry are discussed. An alternative scheme is described that is based on the ICRP effective dose equivalent, H/sub E/, and which is a direct estimate of the average radiation risk to the patient. The mean value of H/sub E/ for seven common /sup 99m/Tc nuclear medicine procedures is 0.46 rem and the average radiation risk from this level of exposure is estimated to be comparable to the risk from smoking approx. 28 packs of cigarettes or driving approx. 1300 miles.

Radiationdose from diagnostic and interventional radiations continues to be a focus of the regulatory, accreditation and standards organizations in the US and Europe. A Joint AAPM/EFOMP effort has been underway in the past year — having the goal to assist the clinical medical physicist with communicating optional and varied approaches in estimating (and validating) patient dose. In particular, the tools provided by DICOM RadiationDose Structured Reports, either by themselves or as part of a networked data repository of dose related information are a rich source of actionable information. The tools of the medical physicist have evolved to include using DICOM data in meaningful ways to look at patient dose with respect to imaging practices. In addition to how accurate or reproducible a dose value is (totally necessary and our traditional workspace) it is now being asked how reproducible (patient to patient, device to device) are the delivered doses (new tasking)? Clinical medical physicists are best equipped to assist our radiology and technologist colleagues with this effort. The purpose of this session is to review the efforts of TG246 - bringing forward a summary content of the TG246 Report including specific dose descriptors for CT and Fluoroscopy — particularly in a focus of leveraging the RDSR as a means for monitoring good practices ALARA. Additionally, rapidly evolving technologies for more refined doseestimates are now in use. These will be presented as they look to having highly patient specific doseestimates in automated use.

The technique details for measuring radiationdose are expounded. The results of gamma and neutron radiation levels are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the photon radiation level move as background for future experiments is measured by a NaI(Tl) detector.

At the Savannah River Site (SRS), emergency response computer models are used to estimatedose following releases of radioactive materials to the environment. Downwind air and ground concentrations and their associated doses from inhalation and ground shine pathways are estimated. The emergency response model (PUFF-PLUME) uses real-time data to track either instantaneous (puff) or continuous (plume) releases. A site-specific ingestion dose model was developed for use with PUFF-PLUME that includes the following ingestion dose pathways pertinent to the surrounding SRS area: milk, beef, water, and fish. The model is simplistic and can be used with existing code output.

Emerging concerns regarding the hazard from medical radiation including CT examinations has been suggested. The purpose of this study was to observe the longitudinal changes of CT radiationdoses of various CT protocols and to estimate the long-term efforts of supervising radiologists to reduce medical radiation. Radiationdose data from 11 representative CT protocols were collected from 12 hospitals. Attending radiologists had collected CT radiationdose data in two time points, 2007 and 2010. They collected the volume CT dose index (CTDIvol) of each phase, number of phases, dose length product (DLP) of each phase, and types of scanned CT machines. From the collected data, total DLP and effective dose (ED) were calculated. CTDIvol, total DLP, and ED of 2007 and 2010 were compared according to CT protocols, CT machine type, and hospital. During the three years, CTDIvol had significantly decreased, except for dynamic CT of the liver. Total DLP and ED were significantly decreased in all 11 protocols. The decrement was more evident in newer CT scanners. However, there was substantial variability of changes of ED during the three years according to hospitals. Although there was variability according to protocols, machines, and hospital, CT radiationdoses were decreased during the 3 years. This study showed the effects of decreased CT radiationdose by efforts of radiologists and medical society. PMID:26908984

Angiotensin-converting enzyme inhibitors (ACEi) are effective mitigators of radiation nephropathy. To date, their experimental use has been in fixed-dose regimens. In clinical use, doses of ACEi and other medication may be escalated to achieve greater benefit. We therefore used a rodent model to test the ACEi enalapril as a mitigator of radiation injury in an escalating-dose regimen. Single-fraction partial-body irradiation (PBI) with one hind limb out of the radiation field was used to model accidental or belligerent radiation exposures. PBI doses of 12.5, 12.75 and 13 Gy were used to establish multi-organ injury. One third of the rats underwent PBI alone, and two thirds of the rats had enalapril started five days after PBI at a dose of 30 mg/l in the drinking water. When there was established azotemic renal injury enalapril was escalated to a 60 mg/l dose in half of the animals and then later to a 120 mg/l dose. Irradiated rats on enalapril had significant mitigation of combined pulmonary and renal morbidity and had significantly less azotemia. Dose escalation of enalapril did not significantly improve outcomes compared to fixed-dose enalapril. The current data support use of the ACEi enalapril at a fixed and clinically usable dose to mitigate radiation injury after partial-body radiation exposure. PMID:26934483

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimatedradiationdose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiationdose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

In the radiology department of the Mexican National Institute of Neurology and Neurosurgery, a dedicated institute in Mexico City, on average 19.3 computed tomography (CT) examinations are performed daily on hospitalized patients for neurological disease diagnosis, control scans and follow-up imaging. The purpose of this work was to estimate the effective dose received by hospitalized patients who underwent a diagnostic CT scan using typical effective dose values for all CT types and to obtain the estimated effective dose distributions received by surgical and non-surgical patients. Effective patient doses were estimated from values per study type reported in the applications guide provided by the scanner manufacturer. This retrospective study included all hospitalized patients who underwent a diagnostic CT scan between 1 January 2011 and 31 December 2012. A total of 8777 CT scans were performed in this two-year period. Simple brain scan was the CT type performed the most (74.3%) followed by contrasted brain scan (6.1%) and head angiotomography (5.7%). The average number of CT scans per patient was 2.83; the average effective dose per patient was 7.9 mSv; the mean estimatedradiationdose was significantly higher for surgical (9.1 mSv) than non-surgical patients (6.0 mSv). Three percent of the patients had 10 or more brain CT scans and exceeded the organ radiationdose threshold set by the International Commission on Radiological Protection for deterministic effects of the eye-lens. Although radiation patient doses from CT scans were in general relatively low, 187 patients received a high effective dose (>20 mSv) and 3% might develop cataract from cumulative doses to the eye lens.

Estimates of the radiationdose to the upper airways including the trachea, oropharnyx, and nasal linings from inhalation of oxygen-15 labeled CO/sub 2/ studies are provided. Three air administration procedures were examined; inhalation by nose, by mouth and by mouth through a mouthpiece. Attention is given to the inhaled radioactive gas absorbed and retained in the mucus and saliva layers lining the respiratory passages. The authors estimates from direct measurements in saliva and mucus of the highest total radiationdose is to the oropharnyx (5.2 rads, mouth; 2.8 rads, nose). The dose to the trachea was estimated to be 3.5 rads from mucus measurements from dogs. The comparative dose to lungs is 1.2 rads (Bigler and Sgouros, JNM 24:431, 1983). These doses are for steady-state measurements involving the breathing of 1 mCi/1-air for 1 hr. Single breath estimates can be obtained by dividing by the number of breaths per hr (720). Although this procedure leads to a 10% reduction in the radiationdose to the lung, the radiationdose to the lining of the vein infused is high, ranging from 70 to 430 rads for equal activity administered. The authors recommend considering the lung as the tissue at highest risk for both inhalation and IV administration procedures.

We have developed a method to register and display 3D parametric data, in particular radiationdose, on two-dimensional endoscopic images. This registration of radiationdose to endoscopic or optical imaging may be valuable in assessment of normal tissue response to radiation, and visualization of radiated tissues in patients receiving post-radiation surgery. Electromagnetic sensors embedded in a flexible endoscope were used to track the position and orientation of the endoscope allowing registration of 2D endoscopic images to CT volumetric images and radiationdoses planned with respect to these images. A surface was rendered from the CT image based on the air/tissue threshold, creating a virtual endoscopic view analogous to the real endoscopic view. Radiationdose at the surface or at known depth below the surface was assigned to each segment of the virtual surface. Dose could be displayed as either a colorwash on this surface or surface isodose lines. By assigning transparency levels to each surface segment based on dose or isoline location, the virtual dose display was overlaid onto the real endoscope image. Spatial accuracy of the dose display was tested using a cylindrical phantom with a treatment plan created for the phantom that matched dose levels with grid lines on the phantom surface. The accuracy of the dose display in these phantoms was 0.8-0.99 mm. To demonstrate clinical feasibility of this approach, the dose display was also tested on clinical data of a patient with laryngeal cancer treated with radiation therapy, with estimated display accuracy of ˜2-3 mm. The utility of the dose display for registration of radiationdose information to the surgical field was further demonstrated in a mock sarcoma case using a leg phantom. With direct overlay of radiationdose on endoscopic imaging, tissue toxicities and tumor response in endoluminal organs can be directly correlated with the actual tissue dose, offering a more nuanced assessment of normal tissue

Rapid innovations in radiation therapy techniques have resulted in an urgent need for risk projection models for second cancer risks from high-doseradiation exposure, because direct observation of the late effects of newer treatments will require patient follow-up for a decade or more. However, the patterns of cancer risk after fractionated high-doseradiation are much less well understood than those after lower-dose exposures (0.1-5 Gy). In particular, there is uncertainty about the shape of the dose-response curve at high doses and about the magnitude of the second cancer risk per unit dose. We reviewed the available evidence from epidemiologic studies of second solid cancers in organs that received high-dose exposure (>5 Gy) from radiation therapy where dose-response curves were estimated from individual organ-specific doses. We included 28 eligible studies with 3434 second cancer patients across 11 second solid cancers. Overall, there was little evidence that the dose-response curve was nonlinear in the direction of a downturn in risk, even at organ doses of ≥60 Gy. Thyroid cancer was the only exception, with evidence of a downturn after 20 Gy. Generally the excess relative risk per Gray, taking account of age and sex, was 5 to 10 times lower than the risk from acute exposures of <2 Gy among the Japanese atomic bomb survivors. However, the magnitude of the reduction in risk varied according to the second cancer. The results of our review provide insights into radiation carcinogenesis from fractionated high-dose exposures and are generally consistent with current theoretical models. The results can be used to refine the development of second solid cancer risk projection models for novel radiation therapy techniques.

Previously, dose determination based on radiation induced stiffness difference measurements has received no or very little attention. Here, a preliminary evaluation of a combined system for dosimetry based on radiation sensitive gels, ultrasonic elastography and a plane strain inverse algorithm is presented. A block of gel was irradiated along one of its axes producing stiff rod-like regions. The dose distribution found with quantitative ultrasound elastography was compared with a reference dose distribution measured with magnetic resonance imaging. In these early results, the high dose areas were clearly detected, while noise in the ultrasound measurement and strong regularisation in the inverse computing introduced shape distortions, noise in the doseestimates and problems estimating the correct dose contrast. Improvements in the experimental setup and inverse computing are possible, for example by acquisition of transversal ultrasound data, which could essentially reduce the noise and restrict direct influence of the experimental boundary condition on the doseestimation by providing additional information for inverse computing. Based on the preliminary results and the potential for improvement it is concluded that further investigations should follow to establish the potential of the rapidly developing field of elastography for measuring radiationdose based on radiation induced changes in stiffness.

The evaluation of the radiationdose during accident in a nuclear reactor is of great concern from the viewpoint of safety. One of important accident must be analyzed and may be occurred in open pool type reactor is the rejection of cobalt device. The study is evaluating the dose rate levels resulting from upset withdrawal of co device especially the radiationdose received by the operator in the control room. Study of indirect radiation exposure to the environment due to skyshine effect is also taken into consideration in order to evaluate the radiationdose levels around the reactor during the ejection trip. Microshield, SHLDUTIL, and MCSky codes were used in this study to calculate the radiationdose profiles during cobalt device ejection trip inside and outside the reactor building. PMID:27423021

Significant quantities of long-lived radionuclides were released to the environment during the Chernobyl nuclear power plant accident in 1986. These radionuclides contributed to radiationdoses due to ingestion of contaminated foods and external exposure from the ground deposition that resulted. The contributions of these exposure pathways to thyroid doses received by subjects of an epidemiologic study of children from Belarus are evaluated and presented. The analysis shows that ingestion of the long-lived radionuclides, primarily radiocesium, typically contributed a small percentage of the total thyroid dose received by the study subjects. The median and mean fractional contributions were 0.76 and 0.95%, respectively. The contribution of external exposure to the thyroid dose was generally larger and more variable, with median and mean contributions of 1.2 and 1.8% of the total thyroid doses, respectively. For regions close to the reactor site, where radionuclide deposition was highest, the contributions of radiocesium ingestion and external exposure were generally lower than those of the short-lived radioiodine isotopes (132I and 133I) and their precursors (132Te). In other areas, the contributions of these two pathways were comparable to those of the short-lived radioiodines. For all subjects, intakes of 131I were the primary source of dose to the thyroid. PMID:16538137

Since Korean Air has begun to use the polar route from Seoul/ICN airport to New York/JFK airport on August 2006, there are explosive needs for the estimation and prediction against cosmic radiation exposure for Korean aircrew and passengers in South Korea from public. To keep pace with those needs of public, Korean government made the law on safety standards and managements of cosmic radiation for the flight attendants and the pilots in 2013. And we have begun to develop our own Korean Radiation Exposure Assessment Model (KREAM) for aviation route dose since last year funded by Korea Meteorological Administration (KMA). GEANT4 model and NRLMSIS 00 model are used for calculation of the energetic particles' transport in the atmosphere and for obtaining the background atmospheric neutral densities depending on altitude. For prediction the radiation exposure in many routes depending on the various space weather effects, we constructed a database from pre-arranged simulations using all possible combinations of R, S, and G, which are the space weather effect scales provided by the National Oceanic and Atmospheric Administration (NOAA). To get the solar energetic particles' spectrum at the 100 km altitude which we set as a top of the atmospheric layers in the KREAM, we use ACE and GOES satellites' proton flux observations. We compare the results between KREAM and the other cosmic radiationestimation programs such as CARI-6M which is provided by the Federal Aviation Agency (FAA). We also validate KREAM's results by comparison with the measurement from Liulin-6K LET spectrometer onboard Korean commercial flights and Korean Air Force reconnaissance flights.

In this work, solar radiationestimations obtained from a satellite and a numerical weather prediction model in mainland Spain have been compared. Similar comparisons have been formerly carried out, but in this case, the methodology used is different: the temporal variability of both sources of estimation has been compared with the annual evolution of the radiation associated to the different study climate zones. The methodology is based on obtaining behavior patterns, using a Principal Component Analysis, following the annual evolution of solar radiationestimations. Indeed, the adjustment degree to these patterns in each point (assessed from maps of correlation) may be associated with the annual radiation variation (assessed from the interquartile range), which is associated, in turn, to different climate zones. In addition, the goodness of each estimation source has been assessed comparing it with data obtained from the radiation measurements in ground by pyranometers. For the study, radiation data from Satellite Application Facilities and data corresponding to the reanalysis carried out by the European Centre for Medium-Range Weather Forecasts have been used.

We present a probabilistic framework to estimate the accumulated radiationdose and the corresponding dose uncertainty that is delivered to important anatomical structures, e.g. the primary tumor and healthy surrounding organs, during radiotherapy. The dose uncertainty we report is a direct result of uncertainties in the estimates of the deformation which aligns the daily cone-beam CT images with the planning CT. The accumulated radiationdose is an important measure to monitor during treatment, in particular to see if it significantly deviates from the planned dose which might indicate that either the patient was not properly positioned before treatment or that the anatomy has changed due to the treatment. In the case of the latter, the treatment plan should be adaptively changed to align with the current patient anatomy. We estimate the accumulated dose distribution, and its uncertainty, retrospectively on a dataset acquired during treatment of cancer in the neck and show the dose distributions in the form of dose volume histograms. PMID:22003661

Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.

This paper describes the results of many studies, both theoretical and experimental, which have been carried out by Urenco over the last 15 years into radiationdose rates from uranium hexafluoride (UF{sub 6}) cylinders. The contents of the cylinder, its history, and the geometry all affect the radiationdose rate. These factors are all examined in detail. Actual and predicted dose rates are compared with levels permitted by IAEA transport regulations.

Cardiac catheterization procedures using fluoroscopy reduce patient morbidity and mortality compared to operative procedures. These diagnostic and therapeutic procedures require radiation exposure to patients and physicians. The objectives of the present investigation were to provide a systematic comprehensive summary of the reported radiationdoses received by operators due to diagnostic or interventional fluoroscopically-guided procedures, to identify the primary factors influencing operator radiationdose, and to evaluate whether there have been temporal changes in the radiationdoses received by operators performing these procedures. Using PubMed, we identified all English-language journal articles and other published data reporting radiation exposures to operators from diagnostic or interventional fluoroscopically-guided cardiovascular procedures from the early 1970's through the present. We abstracted the reported radiationdoses, dose measurement methods, fluoroscopy system used, operational features, radiation protection features, and other relevant data. We calculated effective doses to operators in each study to facilitate comparisons. The effective doses ranged from 0.02-38.0 microSv for DC (diagnostic catheterizations), 0.17-31.2 microSv for PCI (percutaneous coronary interventions), 0.24-9.6 microSv for ablations, and 0.29-17.4 microSv for pacemaker or intracardiac defibrillator implantations. The ratios of doses between various anatomic sites and the thyroid, measured over protective shields, were 0.9 +/- 1.0 for the eye, 1.0 +/- 1.5 for the trunk, and 1.3 +/- 2.0 for the hand. Generally, radiationdose is higher on the left side of an operator's body, because the operator's left side is closer to the primary beam when standing at the patient's right side. Modest operator dose reductions over time were observed for DC and ablation, primarily due to reduction in patient doses due to decreased fluoroscopy/cineradiography time and dose rate by technology

An EXCEL{reg_sign} spreadsheet has been developed that, when combined with the PC version of XOQDOQ, will generate estimates of maximum individual dose from routine atmospheric releases of radionuclides. The spreadsheet, MAXINE, utilizes a variety of atmospheric dispersion factors to calculate radiationdose as recommended by the US Nuclear Regulatory Commission in Regulatory Guide 1.109 [USNRC 1977a]. The methodology suggested herein includes use of both the MAXINE spreadsheet and the PC version of XOQDOQ.

A computer program is described which calculates doses averaged within five major segments of the blood forming organ in the human body taking into account selfshielding of the detailed body geometry and nuclear star effects for proton radiation of arbitrary energy spectrum (energy less than 1 GeV) and isotropic angular distribution. The dose calculation includes the first term of an asymptotic series expansion of transport theory which is known to converge rapidly for most points in the human body. The result is always a conservative estimate of dose and is given as physical dose (rad) and dose equivalent (rem).

Predicting risk of human cancer following exposure of an individual or a population to ionizing radiation is challenging. To an approximation, this is because uncertainties of uniform absorption of dose and the uniform processing of dose-related damage at the cellular level within a complex set of biological variables degrade the confidence of predicting the delayed expression of cancer as a relatively rare event. Cellular biodosimeters that simultaneously report: 1) the quantity of absorbed dose after exposure to ionizing radiation, 2) the quality of radiation delivering that dose, and 3) the risk of developing cancer by the cells absorbing that dose would therefore be useful. An approach to such a multiparametric biodosimeter will be reported. This is the demonstration of a dose responsive field effect of enhanced expression of keratin 18 (K18) in cultures of human mammary epithelial cells irradiated with cesium-1 37 gamma-rays. Dose response of enhanced K18 expression was experimentally extended over a range of 30 to 90 cGy for cells evaluated at mid-log phase. K18 has been reported to be a marker for tumor staging and for apoptosis, and thereby serves as an example of a potential marker for cancer risk, where the reality of such predictive value would require additional experimental development. Since observed radiogenic increase in expression of K18 is a field effect, ie., chronically present in all cells of the irradiated population, it may be hypothesized that K18 expression in specific cells absorbing particulate irradiation, such as the high-LET-producing atomic nuclei of space radiation, will report on both the single-cell distributions of those particles amongst cells within the exposed population, and that the relatively high dose per cell delivered by densely ionizing tracks of those intersecting particles will lead to cell-specific high-expression levels of K18, thereby providing analytical end points that may be used to resolve both the quantity and

High doses of ionizing radiation clearly produce deleterious consequences in humans, including, but not exclusively, cancer induction. At very low radiationdoses the situation is much less clear, but the risks of low-doseradiation are of societal importance in relation to issues as varied as screening tests for cancer, the future of nuclear power, occupational radiation exposure, frequent-flyer risks, manned space exploration, and radiological terrorism. We review the difficulties involved in quantifying the risks of low-doseradiation and address two specific questions. First, what is the lowest dose of x- or gamma-radiation for which good evidence exists of increased cancer risks in humans? The epidemiological data suggest that it is approximately 10-50 mSv for an acute exposure and approximately 50-100 mSv for a protracted exposure. Second, what is the most appropriate way to extrapolate such cancer risk estimates to still lower doses? Given that it is supported by experimentally grounded, quantifiable, biophysical arguments, a linear extrapolation of cancer risks from intermediate to very low doses currently appears to be the most appropriate methodology. This linearity assumption is not necessarily the most conservative approach, and it is likely that it will result in an underestimate of some radiation-induced cancer risks and an overestimate of others. PMID:14610281

Over the last few years, computed tomography (CT) has developed into a standard clinical test for a variety of cardiovascular conditions. The emergence of cardiovascular CT during a period of dramatic increase in radiation exposure to the population from medical procedures and heightened concern about the subsequent potential cancer risk has led to intense scrutiny of the radiation burden of this new technique. This has hastened the development and implementation of dose reduction tools and prompted closer monitoring of patient dose. In an effort to aid the cardiovascular CT community in incorporating patient-centered radiationdose optimization and monitoring strategies into standard practice, the Society of Cardiovascular Computed Tomography has produced a guideline document to review available data and provide recommendations regarding interpretation of radiationdose indices and predictors of risk, appropriate use of scanner acquisition modes and settings, development of algorithms for dose optimization, and establishment of procedures for dose monitoring. PMID:21723512

SJ-10 scientific satellite will be launched after a few years in china. The SJ-10 satellite is a recoverable satellite researching for materials and life science. Orbit altitude of 600 km circular orbit with an inclination of 63 " Space Radiation Biology Researching " is a sub-project in SJ-10 satellite, which will research the relation between the biological effect and space particle's radiation. The project include the biological materials for biological effect researching and "The Detector of Space Radiation Biology " for measurement the dose in the space. In SJ-10 satellite's orbit, The source of the particle radiation is from earth radiation-belt and galaxy cosmic ray . The propose of "The Detector of space radiation biology " is monitor the particle radiation, service to the scientific analysis. The instrument include the semiconductor particle radiation monitoring package and Tissue-equivalent particle radiation monitoring package. The semiconductor particle radiation monitoring package is used to detect the flux of the protons, electrons and heavy ions, also the linear energy transfer(LET) in the silicon material. The element composition of Tissue-equivalent particle radiation monitoring package is similar to the biology issue. It can measure the space particles in biological materials, the value of the LET, dose, dose equivalent, and more Keywords: SJ-10 satellites; radiation biological effects; semiconductor particle radiation moni-toring package; Tissue-equivalent particle radiation monitoring package

A fully detailed Monte Carlo geometrical model of an 18 MV Varian Clinac 2100C medical linear accelerator, lodged at Blida Anti-Cancer Centre in Algeria, was developed during this study to estimate the photoneutrons spectra and doses at the patient table in a radiotherapy treatment room, for radiation protection purposes.

In 1972 committees of the United Nations and the US National Academy of Sciencs emphasized the need for organ doseestimates on the Japanese atomic-bomb survivors. These estimates were then supplied by workers in Japan and the US, and they were used with the so-called T65D estimates of a survivor's radiation exposure to assess risk from radiation. Recently the T65D estimates have been questioned, and programs for reassessment of atomic-bomb radiation dosimetry have been started in Japan and the US. As a part of this new effort a mathematical analogue of the human body (or ''mathematical phantom''), to be used in estimating organ doses in adult survivors, is presented here. Recommendations on organ dosimetry for juvenile survivors are also presented and discussed. 57 refs., 10 figs., 6 tabs.

It has been suggested that a mechanistic understanding of the cellular responses to low dose and dose rate may be valuable in reducing some of the uncertainties involved in current risk estimates for cancer- and non-cancer-related radiation effects that are inherited in the linear no-threshold hypothesis. In this study, the effects of low-doseradiation on the proteome in both human fibroblasts and stem cells were investigated. Particular emphasis was placed on examining: 1. the dose-response relationships for the differential expression of proteins in the low-dose range (40-140 mGy) of low-linear energy transfer (LET) radiation; and 2. the effect on differential expression of proteins of a priming dose given prior to a challenge dose (adaptive response effects). These studies were performed on cultured human fibroblasts (VH10) and human adipose-derived stem cells (ADSC). The results from the VH10 cell experiments demonstrated that low-doses of low-LET radiation induced unique patterns of differentially expressed proteins for each dose investigated. In addition, a low priming radiationdose significantly changed the protein expression induced by the subsequent challenge exposure. In the ADSC the number of differentially expressed proteins was markedly less compared to VH10 cells, indicating that ADSC differ in their intrinsic response to low doses of radiation. The proteomic results are further discussed in terms of possible pathways influenced by low-dose irradiation. PMID:26934482

A Monte Carlo based computer model has been developed for electron beam computed tomography (EBCT) to calculate organ and effective doses in a humanoid hermaphrodite phantom. The program has been validated by comparison with experimental measurements of the CT dose index in standard head and body CT dose phantoms; agreement to better than 8% has been found. The robustness of the model has been established by varying the input parameters. The amount of energy deposited at the 12:00 position of the standard body CT dose phantom is most susceptible to rotation angle, whereas that in the central region is strongly influenced by the beam quality. The program has been used to investigate the changes in organ absorbed doses arising from partial and full rotation about supine and prone subjects. Superficial organs experience the largest changes in absorbed dose with a change in subject orientation and for partial rotation. Effective doses for typical clinical scan protocols have been calculated and compared with values obtained using existing dosimetry techniques based on full rotation. Calculations which make use of Monte Carlo conversion factors for the scanner that best matches the EBCT dosimetric characteristics consistently overestimate the effective dose in supine subjects by typically 20%, and underestimate the effective dose in prone subjects by typically 13%. These factors can therefore be used to correct values obtained in this way. Empirical dosimetric techniques based on the dose-length product yield errors as great as 77%. This is due to the sensitivity of the dose length product to individual scan lengths. The magnitude of these errors is reduced if empirical dosimetric techniques based on the average absorbed dose in the irradiated volume (CTDI{sub vol}) are used. Therefore conversion factors specific to EBCT have been calculated to convert the CTDI{sub vol} to an effective dose.

A number of considerations must go into the process of determining the risk of deleterious effects of space radiation to travelers. Among them are (1) determination of the components of the radiation environment (particle species, fluxes and energy spectra) which will encounter, (2) determination of the effects of shielding provided by the spacecraft and the bodies of the travelers which modify the incident particle spectra and mix of particles, and (3) determination of relevant biological effects of the radiation in the organs of interest. The latter can then lead to an estimation of risk from a given space scenario. Clearly, the process spans many scientific disciplines from solar and cosmic ray physics to radiation transport theeory to the multistage problem of the induction by radiation of initial lesions in living material and their evolution via physical, chemical, and biological processes at the molecular, cellular, and tissue levels to produce the end point of importance.

A number of considerations must go into the process of determining the risk of deleterious effects of space radiation to travelers. Among them are (1) determination of the components of the radiation environment (particle species, fluxes and energy spectra) which will encounter, (2) determination of the effects of shielding provided by the spacecraft and the bodies of the travelers which modify the incident particle spectra and mix of particles, and (3) determination of relevant biological effects of the radiation in the organs of interest. The latter can then lead to an estimation of risk from a given space scenario. Clearly, the process spans many scientific disciplines from solar and cosmic ray physics to radiation transport theeory to the multistage problem of the induction by radiation of initial lesions in living material and their evolution via physical, chemical, and biological processes at the molecular, cellular, and tissue levels to produce the end point of importance.

We review methods and data used for determining astronaut organ dose equivalents on past space missions including Apollo, Skylab, Space Shuttle, NASA-Mir, and International Space Station (ISS). Expectations for future lunar missions are also described. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra, or a related quantity, the lineal energy (y) spectra that is measured by a tissue equivalent proportional counter (TEPC). These data are used in conjunction with space radiation transport models to project organ specific doses used in cancer and other risk projection models. Biodosimetry data from Mir, STS, and ISS missions provide an alternative estimate of organ dose equivalents based on chromosome aberrations. The physical environments inside spacecraft are currently well understood with errors in organ dose projections estimated as less than plus or minus 15%, however understanding the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons for which there are no human data to estimate risks. The accuracy of projections of organ dose equivalents described here must be supplemented with research on the health risks of space exposure to properly assess crew safety for exploration missions.

Purpose: To use Monte Carlo techniques to compute the scatter radiationdose distribution patterns around patients undergoing Interventional Radiological (IR) examinations. Method: MCNP was used to model the scatter radiation air kerma (AK) per unit kerma area product (KAP) distribution around a 24 cm diameter water cylinder irradiated with monoenergetic x-rays. Normalized scatter fractions (SF) were generated defined as the air kerma at a point of interest that has been normalized by the Kerma Area Product incident on the phantom (i.e., AK/KAP). Three regions surrounding the water cylinder were investigated consisting of the area below the water cylinder (i.e., backscatter), above the water cylinder (i.e., forward scatter) and to the sides of the water cylinder (i.e., side scatter). Results: Immediately above and below the water cylinder and in the side scatter region, values of normalized SF decreased with the inverse square of the distance. For z-planes further away, the decrease was exponential. Values of normalized SF around the phantom were generally less than 10-4. Changes in normalized SF with x-ray energy were less than 20% and generally decreased with increasing x-ray energy. At a given distance from region where the x-ray beam enters the phantom, the normalized SF was higher in the backscatter regions, and smaller in the forward scatter regions. The ratio of forward to back scatter normalized SF was lowest at 60 keV and highest at 120 keV. Conclusion: Computed SF values quantify the normalized fractional radiation intensities at the operator location relative to the radiation intensities incident on the patient, where the normalization refers to the beam area that is incident on the patient. SF values can be used to estimate the radiationdose received by personnel within the procedure room, and which depend on the imaging geometry, patient size and location within the room. Monte Carlo techniques have the potential for simulating normalized SF values

Version: 00 MILDOS estimates impacts from radioactive emissions from uranium milling facilities. These impacts are presented as dose commitments to individuals and the regional population within an 80 km radius of the facility. Only airborne releases of radioactive materials are considered: releases to surface water and to groundwater are not addressed in MILDOS. This is a multi-purpose code system, within the range of its proper application, and can be used to evaluate population doses formore » NEPA assessments, maximum individual doses for predictive 40 CFR 190 compliance evaluations, or maximum offsite air concentrations for predictive evaluations of 10 CFR 20 compliance. The MILDOS package includes models for both point sources (stacks, vents) and area sources (ore pads, tailings areas). Gaseous releases are limited to consideration of 222Rn plus ingrowth of daughters. Exposure pathways of concern are assumed to be inhalation of airborne radioactive material, ingestion of vegetables, meat, and milk contaminated via deposition, and external exposure to radiation emitted by airborne activity and activity deposited on ground surfaces. Liquid exposure pathways are not treated by MILDOS.« less

There is now a substantial body of evidence for end points such as oncogenic transformation in vitro, and carcinogenesis and life shortening in vivo, suggesting that dose protraction leads to an increase in effectiveness relative to a single, acute exposure--at least for radiations of medium linear energy transfer (LET) such as neutrons. Table I contains a summary of the pertinent data from studies in which the effect is seen. [table: see text] This phenomenon has come to be known as the "inverse dose rate effect," because it is in marked contrast to the situation at low LET, where protraction in delivery of a dose of radiation, either by fractionation or low dose rate, results in a decreased biological effect; additionally, at medium and high LET, for radiobiological end points such as clonogenic survival, the biological effectiveness is independent of protraction. The quantity and quality of the published reports on the "inverse dose rate effect" leaves little doubt that the effect is real, but the available evidence indicates that the magnitude of the effect is due to a complex interplay between dose, dose rate, and radiation quality. Here, we first summarize the available data on the inverse dose rate effect and suggest that it follows a consistent pattern in regard to dose, dose rate, and radiation quality; second, we describe a model that predicts these features; and, finally, we describe the significance of the effect for radiation protection.

This study is concerned with approximation methods that can be readily applied to estimate the absorbed dose rate from cosmic rays in rads - tissue or rems inside simple geometries of aluminum. The present work is limited to finding the dose rate at the center of spherical shells or behind plane slabs. The dose rate is calculated at tissue-point detectors or for thin layers of tissue. This study considers cosmic-rays dose rates for both free-space and earth-orbiting missions.

In many instances, bone marrow dose equivalents averaged over the entire body have been used as a surrogate for whole-body dose equivalents in space radiation protection studies. However, career radiation limits for space missions are expressed as effective doses. This study compares calculations of effective doses to average bone marrow dose equivalents for several large solar particle events (SPEs) and annual galactic cosmic ray (GCR) spectra, in order to examine the suitability of substituting bone marrow dose equivalents for effective doses. Organ dose equivalents are computed for all radiosensitive organs listed in NCRP Report 116 using the BRYNTRN and HZETRN space radiation transport codes and the Computerized Anatomical Man (CAM) model. These organ dose equivalents are then weighted with the appropriate tissue weighting factors to obtain effective doses. Various thicknesses of aluminum shielding, which are representative of nominal spacecraft and SPE storm shelter configurations, are used in the analyses. For all SPE configurations, the average bone marrow dose equivalent is considerably less than the calculated effective dose. For comparisons of the GCR, there is less than a ten percent difference between the two methods. In all cases, the gonads made up the largest percentage of the effective dose. PMID:12793744

Factors important for characterization of tritium in environmental pathways leading to exposure of man are reviewed and quantification of those factors is discussed. Parameters characterizing the behavior of tritium in man are also subjected to review. Factors to be discussed include organic binding, bioaccumulation, quality factor and transmutation. A variety of models are presently in use to estimatedose to man from environmental releases of tritium. Results from four representative models are compared and discussed. Site-specific information is always preferable when parameterizing models to estimatedose to man. There may be significant differences in dose potential among geographic regions due to variable factors. An example of one such factor examined is absolute humidity. It is concluded that adequate methodologies exist for estimation of dose to man from environmental tritium although a number of areas are identified where additional tritium research is desirable.

We present the Ultraviolet (UV) RadiationDose National Standard for México. The establishment of this measurement reference at Centro Nacional de Metrología (CENAM) eliminates the need of contacting foreign suppliers in the search for traceability towards the SI units when calibrating instruments at 365 nm. Further more, the UV RadiationDose National Standard constitutes a highly accurate and reliable source for the UV radiationdose measurements performed in medical and cosmetic treatments as in the the food and pharmaceutics disinfection processes, among other.

Despite universal consensus that computed tomography (CT) overwhelmingly benefits patients when used for appropriate indications, concerns have been raised regarding the potential risk of cancer induction from CT due to the exponentially increased use of CT in medicine. Keeping radiationdose as low as reasonably achievable, consistent with the diagnostic task, remains the most important strategy for decreasing this potential risk. This article summarizes the general technical strategies that are commonly used for radiationdose management in CT. Dose-management strategies for pediatric CT, cardiac CT, dual-energy CT, CT perfusion and interventional CT are specifically discussed, and future perspectives on CT dose reduction are presented. PMID:22308169

In this paper, the authors recommend that the dose and dose-rate effectiveness factor used for space radiation risk assessments should be based on a comparison of the biological effects of energetic electrons produced along a cosmic ray particles path in low fluence exposures to high dose-rate gamma-ray exposures of doses of about 1 Gy. Methods to implement this approach are described. PMID:26808878

Abstract. Dynamic contrast-enhanced computed tomography (CT) could provide an accurate and widely available technique for myocardial blood flow (MBF) estimation to aid in the diagnosis and treatment of coronary artery disease. However, one of its primary limitations is the radiationdose imparted to the patient. We are exploring techniques to reduce the patient dose by either reducing the tube current or by reducing the number of temporal frames in the dynamic CT sequence. Both of these dose reduction techniques result in noisy data. In order to extract the MBF information from the noisy acquisitions, we have explored several data-domain smoothing techniques. In this work, we investigate two specific smoothing techniques: the sinogram restoration technique in both the spatial and temporal domains and the use of the Karhunen–Loeve (KL) transform to provide temporal smoothing in the sinogram domain. The KL transform smoothing technique has been previously applied to dynamic image sequences in positron emission tomography. We apply a quantitative two-compartment blood flow model to estimate MBF from the time-attenuation curves and determine which smoothing method provides the most accurate MBF estimates in a series of simulations of different dose levels, dynamic contrast-enhanced cardiac CT acquisitions. As measured by root mean square percentage error (% RMSE) in MBF estimates, sinogram smoothing generally provides the best MBF estimates except for the cases of the lowest simulated dose levels (tube current=25 mAs, 2 or 3 s temporal spacing), where the KL transform method provides the best MBF estimates. The KL transform technique provides improved MBF estimates compared to conventional processing only at very low doses (<7 mSv). Results suggest that the proposed smoothing techniques could provide high fidelity MBF information and allow for substantial radiationdose savings. PMID:25642441

At the Savannah River Site (SRS), emergency response models estimatedose for inhalation and ground shine pathways. A methodology has been developed to incorporate ingestion doses into the emergency response models. The methodology follows a two-phase approach. The first phase estimates site-specific derived response levels (DRLs) which can be compared with predicted ground-level concentrations to determine if intervention is needed to protect the public. This phase uses accepted methods with little deviation from recommended guidance. The second phase uses site-specific data to estimate a 'best estimate' dose to offsite individuals from ingestion of foodstuffs. While this method deviates from recommended guidance, it is technically defensibly and more realistic. As guidance is updated, these methods also will need to be updated.

The aim of this study was to quantify stray radiationdose from neutrons emanating from a proton treatment unit and to evaluate methods of reducing this dose for a pediatric patient undergoing craniospinal irradiation. The organ equivalent doses and effective dose from stray radiation were estimated for a 30.6-Gy treatment using Monte Carlo simulations of a passive scattering treatment unit and a patient-specific voxelized anatomy. The treatment plan was based on computed tomography images of a 10-yr-old male patient. The contribution to stray radiation was evaluated for the standard nozzle and for the same nozzle but with modest modifications to suppress stray radiation. The modifications included enhancing the local shielding between the patient and the primary external neutron source and increasing the distance between them. The effective dose from stray radiation emanating from the standard nozzle was 322 mSv; enhancements to the nozzle reduced the effective dose by as much as 43%. These results add to the body of evidence that modest enhancements to the treatment unit can reduce substantially the effective dose from stray radiation. PMID:20865143

Purpose: Current methods for the estimation of conceptus dose from multidetector CT (MDCT) examinations performed on the mother provide dose data for typical protocols with a fixed scan length. However, modified low-dose imaging protocols are frequently used during pregnancy. The purpose of the current study was to develop a method for the estimation of conceptus dose from any MDCT examination of the trunk performed during all stages of gestation. Methods: The Monte Carlo N-Particle (MCNP) radiation transport code was employed in this study to model the Siemens Sensation 16 and Sensation 64 MDCT scanners. Four mathematical phantoms were used, simulating women at 0, 3, 6, and 9 months of gestation. The contribution to the conceptus dose from single simulated scans was obtained at various positions across the phantoms. To investigate the effect of maternal body size and conceptus depth on conceptus dose, phantoms of different sizes were produced by adding layers of adipose tissue around the trunk of the mathematical phantoms. To verify MCNP results, conceptus dose measurements were carried out by means of three physical anthropomorphic phantoms, simulating pregnancy at 0, 3, and 6 months of gestation and thermoluminescence dosimetry (TLD) crystals. Results: The results consist of Monte Carlo-generated normalized conceptus dose coefficients for single scans across the four mathematical phantoms. These coefficients were defined as the conceptus dose contribution from a single scan divided by the CTDI free-in-air measured with identical scanning parameters. Data have been produced to take into account the effect of maternal body size and conceptus position variations on conceptus dose. Conceptus doses measured with TLD crystals showed a difference of up to 19% compared to those estimated by mathematical simulations. Conclusions: Estimation of conceptus doses from MDCT examinations of the trunk performed on pregnant patients during all stages of gestation can be made

Accumulated evidence has shown that exposure to low-doseradiation, especially doses less than 0.1 Gy, induces observable effects on mammalian cells. However, the underlying molecular mechanisms have not yet been clarified. Recently, it has been shown that low-doseradiation stimulates growth factor receptor, which results in a sequential activation of the mitogen-activated protein kinase pathway. In addition to the activation of the membrane-bound pathways, it is becoming evident that nuclear pathways are also activated by low-doseradiation. Ionizing radiation has detrimental effects on chromatin structure, since radiation-induced DNA double-strand breaks result in discontinuity of nucleosomes. Recently, it has been shown that ATM protein, the product of the ATM gene mutated in ataxia-telangiectasia, recognizes alteration in the chromatin structure, and it is activated through intermolecular autophosphorylation at serine 1981. Using antibodies against phosphorylated ATM, we found that the activated and phosphorylated ATM protein is detected as discrete foci in the nucleus between doses of 10 mGy and 1 Gy. Interestingly, the size of the foci induced by low-doseradiation was equivalent to the foci induced by high-doseradiation. These results indicate that the initial signal is amplified through foci growth, and cells evolve a system by which they can respond to a small number of DNA double-strand breaks. From these results, it can be concluded that low-doseradiation is sensed both in the membrane and in the nucleus, and activation of multiple signal transduction pathways could be involved in manifestations of low-dose effects. PMID:17016017

After the 9.0 magnitude earthquake and subsequent massive tsunami on 11 March 2011 in Japan, several reactors at the Fukushima Daiichi Nuclear Power Plant suffered severe damage. There was immediate participation of U.S. Navy vessels and other United States Department of Defense (DoD) teams that were already in the area at the time of the disaster or arrived shortly thereafter. The correct determination of occupational dose equivalent requires estimation of the background dose component measured by control dosimeters, which is subsequently subtracted from the total dose equivalent measured by personal dosimeters. The purpose of the control dosimeters is to determine the amount of radiationdose equivalent that has accumulated on the dosimeter from background or other non-occupational sources while they are in transit or being stored. Given the release of radioactive material and potential exposure to radiation from the Fukushima Daiichi Nuclear Power Plant and the process by which the U.S. Navy calculates occupational exposure to ionizing radiation, analysis of pre- and post-event control dosimeters is warranted. Several hundred historical dose records from the Naval Dosimetry Center (NDC) database were analyzed and compared with the post-accident dose equivalent data of control dosimeters. As result, it was shown that the dose contribution of the radiation and released radiological materials from the Fukushima nuclear accident to background radiationdoses is less than 0.375 μSv d for shallow and deep photon dose equivalent. There is no measurable effect on neutron background exposure. The latter has at least two important conclusions. First, the NDC can use doses measured by control dosimeters at issuing sites in Japan for determination of personnel dose equivalents; second, the dose data from control dosimeters prior to and after the Fukushima accident may be used to assist in dose reconstruction of non-radiological (non-badged) personnel at these locations

Post-irradiation identification and doseestimation are required to assess the radiation-induced effects on living things in any nuclear emergency. In this study, radiation-induced morphological/cytological changes i.e., number of root formation and its length, shooting length, reduction in mitotic index, micronuclei formation and chromosomal aberrations in the root tip cells of gamma-irradiated onions at lower doses (50-2000 cGy) are reported. The capabilities of this biological species to store the radiation-induced information are also studied. PMID:11762393

The purpose of this study was to investigate the possibility of estimating pediatric thyroid doses from CT using surface neck doses. Optically stimulated luminescence dosimeters were used to measure the neck surface dose of 25 children ranging in ages between one and three years old. The neck circumference for each child was measured. The relationship between obtained surface doses and thyroid dose was studied using acrylic phantoms of various sizes and with holes of different depths. The ratios of hole-to-surface doses were used to convert patients' surface dose to thyroid dose. ImPACT software was utilized to calculate thyroid dose after applying the appropriate age correction factors. A paired t-test was performed to compare thyroid doses from our approach and ImPACT. The ratio of thyroid to surface dose was found to be 1.1. Thyroid doses ranged from 20 to 80 mGy. Comparison showed no statistical significance (p = 0.18). In addition, the average of surface dose variation along the z-axis in helical scans was studied and found to range between 5% (in 10 cm diameter phantom/24 mm collimation/pitch 1.0) and 8% (in 16 cm diameter phantom/12 mm collimation/pitch 0.7). We conclude that surface dose is an acceptable predictor for pediatric thyroid dose from CT. The uncertainty due to surface dose variability may be reduced if narrower collimation is used with a pitch factor close to 1.0. Also, the results did not show any effect of thyroid depth on the measured dose.

The available dose/volume/outcome data for rectal injury were reviewed. The volume of rectum receiving >=60Gy is consistently associated with the risk of Grade >=2 rectal toxicity or rectal bleeding. Parameters for the Lyman-Kutcher-Burman normal tissue complication probability model from four clinical series are remarkably consistent, suggesting that high doses are predominant in determining the risk of toxicity. The best overall estimates (95% confidence interval) of the Lyman-Kutcher-Burman model parameters are n = 0.09 (0.04-0.14); m = 0.13 (0.10-0.17); and TD{sub 50} = 76.9 (73.7-80.1) Gy. Most of the models of late radiation toxicity come from three-dimensional conformal radiotherapy dose-escalation studies of early-stage prostate cancer. It is possible that intensity-modulated radiotherapy or proton beam dose distributions require modification of these models because of the inherent differences in low and intermediate dose distributions.

Because systems that reduce radiation exposure during diagnostic procedures must be developed, significant time and financial resources have been invested in constructing radiationdose management systems. In the present study, the characteristics of an existing ionization-based system were compared to those of a system based on the kinetic energy released per unit mass (KERMA). Furthermore, the feasibility of using the KERMA-based system for patient radiationdose management was verified. The ionization-based system corrected the effects resulting from radiation parameter perturbations in general radiography whereas the KERMA-based system did not. Because of this difference, the KERMA-based radiationdose management system might overestimate the patient's radiationdose due to changes in the radiation conditions. Therefore, if a correction factor describing the correlation between the systems is applied to resolve this issue, then a radiationdose management system can be developed that will enable real-time measurement of the patient's radiation exposure and acquisition of diagnostic images.

Lynette Tew and Becky Farnsworth are decendents whose relatives are litigants in Timothy vs US. The litigants allege that the decendents were harmed by radiationdoses received as a result of local fallout from the testing of nuclear weapons at the Nevada Test Site. We have calculated a best estimate of the whole body dose received by each decendent from external exposure and the ingestion of radionuclides with food. In each case the dose via ingestion is trivial compared to the external dose. For Lynette Tew the doseestimate is 0.28 rads. For Becky Farnsworth it is 0.0035 rads. 23 references, 4 tables.

The comparison of different dose-time-fractionation schedules requires the use of an isoeffect formula. In recent years, the NSD isoeffect formula has been heavily criticized. In this report, we consider an isoeffect formula which is specifically developed for radiation-induced lung damage. The formula is based on the linear-quadratic model and includes a factor for overall treatment time. The proposed procedures allow for the simultaneous derivation of an alpha/beta ratio and a gamma/beta time factor. From animal data in the literature, the derived alpha/beta and gamma/beta ratios for acute lung damage are 5.0 +/- 1.0 Gy and 2.7 +/- 1.4 Gy2/day respectively, while for late damage the suggested values are 2.0 Gy and 0.0 Gy2/day. Data from two clinical studies, one prospective and the other retrospective, were also analysed and corresponding alpha/beta and gamma/beta ratios were determined. For the prospective clinical study, with a limited range of doses per fraction, the resultant alpha/beta and gamma/beta ratios were 0.9 +/- 2.6 Gy and 2.6 +/- 2.5 Gy2/day. The combination of the retrospective and prospective data yielded alpha/beta and gamma/beta ratios of 3.3 +/- 1.5 Gy and 2.4 +/- 1.5 Gy2/day, respectively. One potential advantage of this isoeffect formalism is that it might possibly be applied to both acute and late lung damage. The results of this formulation for acute lung damage indicate that time-dependent effects such as slow repair or proliferation might be more important in determining isoeffect doses than previously predicted by the estimated single dose (ED) formula. Although we present this as an alternative approach, we would caution against its clinical use until its applicability has been confirmed by additional clinical data. PMID:2928557

The aim of this study was to obtain data on the biodistribution of (64)CuCl2 in rats and to obtain estimates of the radiationdoses to humans by extrapolating the animal data. MicroPET imaging and biodistribution studies were carried out with Wistar rats, and the doses were estimated with OLINDA/EXM. The lower large intestine wall was found to be the critical organ with an absorbed dose of 139±34 and 125±32µGy/MBq for females and males, respectively. The corresponding effective doses were estimated as 47±4 and 39±4µSv/MBq. PMID:27295514

At the outset of the accident at Fukushima Daiichi Nuclear Power Plant in March 2011, the radiationdoses experienced by residents were calculated from the readings at monitoring posts, with several assumptions being made from the point of view of protection and safety. However, health effects should also be estimated by obtaining measurements of the individual radiationdoses. The individual external radiationdoses, determined by a behavior survey in the "evacuation and deliberate evacuation area" in the first 4 months, were <5 mSv in 97.4% of residents (maximum: 15 mSv). Doses in Fukushima Prefecture were <3 mSv in 99.3% of 386,572 residents analyzed. External doses in Fukushima City determined by personal dosimeters were <1 mSv/3 months (September-November, 2011) in 99.7% of residents (maximum: 2.7 mSv). Thyroid radiationdoses, determined in March using a NaI (TI) scintillation survey meter in children in the evacuation and deliberate evacuation area, were <10 mSv in 95.7% of children (maximum: 35 mSv). Therefore, all doses were less than the intervention level of 50 mSv proposed by international organizations. Internal radiationdoses determined by cesium-134 ((134)C) and cesium-137 ((137)C) whole-body counters (WBCs) were <1 mSv in 99% of the residents, and the maximum thyroid equivalent dose by iodine-131 WBCs was 20 mSv. The exploratory committee of the Fukushima Health Management Survey mentions on its website that radiation from the accident is unlikely to be a cause of adverse health effects in the future. In any event, sincere scientific efforts must continue to obtain individual radiationdoses that are as accurate as possible. However, observation of the health effects of the radiationdoses described above will require reevaluation of the protocol used for determining adverse health effects. The dose-response relationship is crucial, and the aim of the survey should be to collect sufficient data to confirm the presence or absence of radiation health

A study has been carried out to assess the radiation exposure from cosmic-ray neutrons to the embryo and foetus of pregnant aircrew and air travellers in consideration of the radiation exposure from cosmic-ray neutrons to the embryo and foetus. A Monte Carlo analysis was performed to determine the equivalent dose from neutrons to the brain and body of an embryo at 8 weeks and to the foetus at the 3, 6 and 9 month periods. Neutron fluence-to-absorbed dose conversion coefficients for the foetal brain and for the entire foetal body (isotropic irradiation geometry) have been determined at the four developmental stages. The equivalent dose rate to the foetus during commercial flights has been further evaluated considering the fluence-to-absorbed dose conversion coefficients, a neutron spectrum measured at an altitude of 11.3 km and an ICRP-92 radiation-weighting factor for neutrons. This study indicates that the foetus can exceed the annual dose limit of 1 mSv for the general public after, for example, 15 round trips on commercial trans-Atlantic flights. PMID:15860538

The observational evidence for radiation-induced health effects in humans comes largely from the exposures to high doses received over short periods of time. The rate of induction of any health risk at low doses and dose rates is estimated by extrapolation from observations at high doses. Effects of low dose/low dose rate could be done by the study of populations that have been exposed to slightly above-average natural radiationdoses. Southwest coastal line of the Kerala state in India is one such region known to have elevated levels of background radioactivity mainly due to the mineral-rich sand available with high abundance of thorium. In the present work, a study was conducted to investigate the inhalation and external radiationdoses to human beings in the high background radiation area along the southwest coast of Kerala. Five hundred dwellings were selected for the study. All the selected houses were at least 10 y old with similar construction. Long-term integrated indoor measurements of the external gamma dose using thermoluminescent dosemeters (TLDs) and the inhalation dose with the SSNTD-based twin-cup dosemeters were carried out in the dwellings simultaneously. Ambient gamma dose measurements were also made with a GM tube-based survey meter while deploying and retrieving the dosemeters. The data show a high degree of heterogeneity. The inhalation dose was found to vary from 0.1 to 3.53 mSv y(-1) and the external dose rates had a range of 383-11419 µGy y(-1). The external doses measured by the survey meter and TLDs showed an excellent correlation. PMID:22961502

The dose and dose equivalent from galactic cosmic radiation outside the magnetosphere were computed. The principal radiation components considered include primary cosmic rays, spallation fragments of the heavy ions, and secondary products (protons, neutrons, alphas, and recoil nuclei) from interactions in tissue. Three mission environments were considered: free space, the lunar surface, and the martian surface. The annual dose equivalents to the blood-forming organs in these environments are approximately 500 mSv, 250 mSv, and 120 mSv, respectively (1 mSv = 0.1 rem). The dose on the lunar surface is one-half of free space because there is only a single hemisphere of exposure. The dose on the martian surface is half again the dose on the moon because of the shielding provided by a thin, carbon dioxide atmosphere. Dose versus aluminum shielding thickness functions have been computed for the free space exposure. Galactic cosmic radiation is energetic and highly penetrating. 30 cm of aluminum shielding reduces the dose equivalent 25% to 40% (depending on the phase of the solar cycle). Aiming for conformity with the draft NCRP annual dose limit for space station crew members, which is 500 mSv/yr, we recommend 7.5 cm of aluminum shielding in all habitable areas of spacecraft designed for long-duration missions outside Earth's magnetosphere. This shielding thickness reduces the galactic cosmic ray dose and diminishes the risk to astronauts from energetic particle events.

The space environment is made up of many different kinds of radiation so that the proper use of biomarkers is essential to estimateradiation risk. This presentation will evaluate differences between biomarkers of dose and risk and demonstrate why they should not be confused following radiation exposures in deep space. Dose is a physical quantity, while risk is a biological quantity. Many examples exist w ereh dose or changes in biomarkers of dose are inappropriately used as predictors of risk. Without information on the biology of the system, the biomarkers of dose provide little help in predicting risk in tissues or radiation exposure types where no excess risk can be demonstrated. Many of these biomarkers of dose only reflect changes in radiationdose or exposure. However, these markers are often incorrectly used to predict risk. For example, exposure of the trachea or of the deep lung to high-LET alpha particles results in similar changes in the biomarker chromosome damage in these two tissues. Such an observation would predict that the risk for cancer induction would be similar in these two tissues. It has been noted , however, that there has never been a tracheal tumor observed in rats that inhaled radon, but with the same exposure, large numbers of tumors were produced in the deep lung. The biology of the different tissues is the major determinant of the risk rather than the radiationdose. Recognition of this fact has resulted in the generation of tissue weighting factors for use in radiation protection. When tissue weighting factors are used the values derived are still called "dose". It is important to recognize that tissue specific observations have been corrected to reflect risk, and therefore should no longer be viewed as dose. The relative biological effectiveness (RBE) is also used to estimateradiation risk. The use of biomarkers to derive RBE is a difficult since it involves the use of a biological response to a standard low-LET reference radiation

This report presents internal radiationdose conversion factors for radionuclides of interest in environmental assessments of nuclear fuel cycles. This volume provides an updated summary of estimates of committed dose equivalent for radionuclides considered in three previous Oak Ridge National Laboratory (ORNL) reports. Intakes by inhalation and ingestion are considered. The International Commission on Radiological Protection (ICRP) Task Group Lung Model has been used to simulate the deposition and retention of particulate matter in the respiratory tract. Results corresponding to activity median aerodynamic diameters (AMAD) of 0.3, 1.0, and 5.0 ..mu..m are given. The gastorintestinal (GI) tract has been represented by a four-segment catenary model with exponential transfer of radioactivity from one segment to the next. Retention of radionuclides in systemic organs is characterized by linear combinations of decaying exponential functions, recommended in ICRP Publication 30. The first-year annual dose rate, maximum annual dose rate, and fifty-year dose commitment per microcurie intake of each radionuclide is given for selected target organs and the effective dose equivalent. These estimates include contributions from specified source organs plus the systemic activity residing in the rest of the body; cross irradiation due to penetrating radiations has been incorporated into these estimates. 15 references.

Relativistic solar proton events GLEs those events with protons having sufficient kinetic energy to initiate a nuclear cascade in the atmosphere can make a contribution to radiationdose at aircraft altitudes We show that it is possible to obtain proper estimates of the expected radiationdose at aircraft altitudes from the analysis of ground-level neutron monitor data Assuming a nominal GLE spectrum the radiationdose at 40 000 feet during a 100 increase at polar latitudes will be in the range of 5 to 10 micro Sieverts per hour depending on the spectral slope An analysis of the large GLE s that have occurred during the past two solar cycles shows that there have been no events where the hourly averaged radiationdose at 40 000 feet would have exceeded 20 micro Sieverts per hour In the past improper GLE analysis was used to estimate the radiationdose at aircraft altitudes The old values derived for the early GLE s resulted in the prediction of high dose rates that persist today as urban legends and contribute to the public concept that the radiationdose at aircraft altitudes is dangerous We demonstrate that modern analytical techniques result in computed radiationdoses during high-energy solar cosmic ray events that are orders of magnitude lower than those obtained by the old techniques We show that the use of the old technique of using straight line power law spectra to extrapolate the flux derived at 1 GeV results in order of magnitude errors when these flux values are extrapolated to lower energies and used to

Pacific Northwest Laboratory is conducting the Hanford Environmental Dose Reconstruction Project to estimate the radiationdoses people may have received from historical Hanford Site operations. Under the direction of an independent Technical Steering Panel, the project is being conducted in phases. The objective of the first phase is to assess the feasibility of the project-wide technical approach for acquiring data and developing models needed to calculate potential radiationdoses. This report summarizes data that were generated for the Phase 1 dose calculations. These included monthly average concentrations of specific radionuclides in Columbia River water and sediments between Priest Rapids Dam and McNary Dam for the years 1964 to 1966. Nine key radionuclides were selected for analysis based on estimation of their contribution to dose. Concentrations of these radionuclides in the river were estimated using existing measurements and hydraulic calculations based on the simplifying assumption that dilution and decay were the primary processes controlling the fate of radionuclides released to the river. Five sub-reaches between Priest Rapids Dam and McNary Dam, corresponding to population centers and tributary confluences, were identified and monthly average radionuclide concentrations were calculated for each sub-reach. The hydraulic calculations were performed to provide radionuclide concentration estimates for time periods and geographic locations where measured data were not available. The validity of the calculation method will be evaluated in Phase 2. 12 refs., 13 figs., 49 tabs.

The Radiological Environment Modeling System (REMS) quantifies dose to humans in radiation environments using the IGRIP (Interactive Graphical Robot Instruction Program) and Deneb/ERGO (Ergonomics) simulation software products. These commercially available products are augmented with custom C code to provide the radiation exposure information to and collect the radiationdose information from the workcell simulations. The emphasis of this paper is on the IGRIP and Deneb/ERGO parts of REMS, since that represents the extension to existing capabilities developed by the authors. Through the use of any radiation transport code or measured data, a radiation exposure input database may be formulated. User-specified IGRIP simulations utilize these database files to compute and accumulate dose to human devices (Deneb`s ERGO human) during simulated operations around radiation sources. Timing, distances, shielding, and human activity may be modeled accurately in the simulations. The accumulated dose is recorded in output files, and the user is able to process and view this output. REMS was developed because the proposed reduction in the yearly radiation exposure limit will preclude or require changes in many of the manual operations currently being utilized in the Weapons Complex. This is particularly relevant in the area of dismantlement activities at the Pantex Plant in Amarillo, TX. Therefore, a capability was needed to be able to quantify the dose associated with certain manual processes so that the benefits of automation could be identified and understood.

The relationship between biological effects and low doses of absorbed radiation is still uncertain, especially for high LET radiation exposure. Estimates of risks from low-dose and low-dose-rates are often extrapolated using data from Japanese atomic bomb survivor with either linear or linear quadratic models of fit. In this study, chromosome aberrations were measured in human peripheral blood lymphocytes and normal skin fibroblasts cells after exposure to very low dose (0.01 - 0.20 Gy) of 170 MeV/u Si-28 ions or 600 MeV/u Fe-56 ions, including doses where on average less than one direct ion traversal per cell nucleus occurs. Chromosomes were analyzed using the whole-chromosome fluorescence in situ hybridization (FISH) technique during the first cell division after irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving >2 breaks in 2 or more chromosomes). The responses for doses above 0.1 Gy (more than one ion traverses a cell) showed linear dose responses. However, for doses less than 0.1 Gy, both Si-28 ions and Fe-56 ions showed a dose independent response above background chromosome aberrations frequencies. Possible explanations for our results are non-targeted effects due to aberrant cell signaling [1], or delta-ray dose fluctuations [2] where a fraction of cells receive significant delta-ray doses due to the contributions of multiple ion tracks that do not directly traverse cell nuclei where chromosome aberrations are scored.

The relationship between biological effects and low doses of absorbed radiation is still uncertain, especially for high LET radiation exposure. Estimates of risks from low-dose and low-dose-rates are often extrapolated using data from Japanese atomic bomb survivors with either linear or linear quadratic models of fit. In this study, chromosome aberrations were measured in human peripheral blood lymphocytes and normal skin fibroblasts cells after exposure to very low dose (1-20 cGy) of 170 MeV/u Si-28- ions or 600 MeV/u Fe-56-ions. Chromosomes were analyzed using the whole chromosome fluorescence in situ hybridization (FISH) technique during the first cell division after irradiation, and chromosome aberrations were identified as either simple exchanges (translocations and dicentrics) or complex exchanges (involving greater than 2 breaks in 2 or more chromosomes). The curves for doses above 10 cGy were fitted with linear or linear-quadratic functions. For Si-28- ions no dose response was observed in the 2-10 cGy dose range, suggesting a non-target effect in this range.

Methods to assess radiationdoses from nuclear weapons test fallout have been used to estimatedoses to populations and individuals in a number of studies. However, only a few epidemiology studies have relied on fallout doseestimates. Though the methods for assessing doses from local and regional compared to global fallout are similar, there are significant differences in predicted doses and contributing radionuclides depending on the source of the fallout, e.g. whether the nuclear debris originated in Nevada at the U.S. nuclear test site or whether it originated at other locations worldwide. The sparse historical measurement data available are generally sufficient to estimate external exposure doses reasonably well. However, reconstruction of doses to body organs from ingestion and inhalation of radionuclides is significantly more complex and is almost always more uncertain than are external doseestimates. Internal doseestimates are generally based on estimates of the ground deposition per unit area of specific radionuclides and subsequent transport of radionuclides through the food chain. A number of technical challenges to correctly modeling deposition of fallout under wet and dry atmospheric conditions still remain, particularly at close-in locations where sizes of deposited particles vary significantly over modest changes in distance. This paper summarizes the various methods of doseestimation from weapons test fallout and the most important dose assessment and epidemiology studies that have relied on those methods. PMID:16808609

The main objective of radiation risk assessment is to determine the risk of various adverse health effects associated with exposure to low doses and low dose rates. Extrapolation of risks from studies of persons exposed at high doses (generally exceeding 1 Sv) and dose rates has been the primary approach used to achieve this objective. The study of Japanese atomic bomb survivors in Hiroshima and Nagasaki has played an especially important role in risk assessment efforts. A direct assessment of the dose-response function based on studies of persons exposed at low doses and dose rates is obviously desirable. This paper focuses on the potential of both current and future nuclear workers studies for investigating the dose-response functions at low doses, and also discusses analyses making use of the low dose portion of the atomic bomb survivor data. Difficulties in using these data are the statistical imprecision of estimateddose-response parameters, and potential bias resulting from confounding factors and from uncertainties in doseestimates.

The radiological transportation risk & consequence program, RADTRAN, has recently added an updated loss of lead shielding (LOS) model to it most recent version, RADTRAN 6.0. The LOS model was used to determine doseestimates to first-responders during a spent nuclear fuel transportation accident. Results varied according to the following: type of accident scenario, percent of lead slump, distance to shipment, and time spent in the area. This document presents a method of creating doseestimates for first-responders using RADTRAN with potential accident scenarios. This may be of particular interest in the event of high speed accidents or fires involving cask punctures.

The notion of a dose-response relationship was probably invented shortly after the discovery of poisons, the invention of alcoholic beverages, and the bringing of fire into a confined space in the forgotten depths of ancient prehistory. The amount of poison or medicine ingested can easily be observed to affect the behavior, health, or sickness outcome. Threshold effects, such as death, could be easily understood for intoxicants, medicine, and poisons. As Paracelsus (1493-1541), the 'father' of modern toxicology said, 'It is the dose that makes the poison.' Perhaps less obvious is the fact that implicit in such dose-response relationships is also the notion of dose rate. Usually, the dose is administered fairly acutely, in a single injection, pill, or swallow; a few puffs on a pipe; or a meal of eating or drinking. The same amount of intoxicants, medicine, or poisons administered over a week or month might have little or no observable effect. Thus, before the discovery of ionizing radiation in the late 19th century, toxicology ('the science of poisons') and pharmacology had deeply ingrained notions of dose-response relationships. This chapter demonstrates that the notion of a dose-response relationship for ionizing radiation is hopelessly simplistic from a scientific standpoint. While useful from a policy or regulatory standpoint, dose-response relationships cannot possibly convey enough information to describe the problem from a quantitative view of radiation biology, nor can they address societal values. Three sections of this chapter address the concepts, observations, and theories that contribute to the scientific input to the practice of managing risks from exposure to ionizing radiation. The presentation begins with irradiation regimes, followed by responses to high and low doses of ionizing radiation, and a discussion of how all of this can inform radiation risk management. The knowledge that is really needed for prediction of individual risk is presented

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiationdose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiationdose level is low. Nevertheless, analysis suggests

A 47-year-old man had a spindly malignant melanoma of the tongue many years after low-doseradiation therapy for lichen planus. To our knowledge, only 12 melanomas of the tongue have been reported previously, and in none of these was radiation documented.

The actual radiationdose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimatedose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media. 57 figs.

The actual radiationdose absorbed in the body is calculated using three-dimensional Monte Carlo transport. Neutrons, protons, deuterons, tritons, helium-3, alpha particles, photons, electrons, and positrons are transported in a completely coupled manner, using this Monte Carlo All-Particle Method (MCAPM). The major elements of the invention include: computer hardware, user description of the patient, description of the radiation source, physical databases, Monte Carlo transport, and output of dose distributions. This facilitated the estimation of dose distributions on a Cartesian grid for neutrons, photons, electrons, positrons, and heavy charged-particles incident on any biological target, with resolutions ranging from microns to centimeters. Calculations can be extended to estimatedose distributions on general-geometry (non-Cartesian) grids for biological and/or non-biological media.

The lunar neutron albedo from thermal energies to 8 MeV was measured on the Lunar Prospector Mission in 1998-1999. Using GEANT4 we have calculated the neutron albedo due to cosmic ray bombardment of the moon and found a good-agreement with the measured fast neutron spectra. We then calculated the total effective dose from neutron albedo of all energies, and made comparisons with the effective dose contributions from both galactic cosmic rays and solar particle events to be expected on the lunar surface.

Prominent among media items related to the Three Mile Island episode were prophecies of future cancers. The credibility of some of these estimates are discussed. The average person has been exposed by the age of 50 to 2.5 rad (0.025 Gy) from natural background. We define low doses as under 25 rad (0.25 Gy). The most heavily exposed members of the general population during the Three Mile Island event received 83 mrad (0.83 mGy). Those exposed to 2500 mrad (25 mGy) would show no pathologically recognizable effects of radiation though there is evidence that chromosomal damage may occur with doses about 1 rad (0.01 Gy). An official stated among the consequences of the Three Mile Island accident that two additional cancer deaths would result. No epidemiologist could detect such an increase in the population at risk. It has been generally agreed that the linear hypothesis is useful for determining protection standards, not prognosis. Objective criteria for pathologic diagnosis of cause-effect relations are presented. PMID:7430985

We revise the spectral technique for estimatingradiated energy from recordings of large earthquakes at regional distances (?? 27.5 km from the source, we model the geometrical spreading of the regional wavefield as r-?? where???? = 0.5 for f ??? 0.2 Hz and ?? = 0.7 for f ??? 0.25 Hz. We fit the spectral falloff with distance using a frequency-dependent attenuation Q = 400(f/1.5)0.6, where Q = 400 for f ??? 1.5 Hz. There is little directivity apparent in the corrected velocity spectra: the velocity spectra observed to the northwest along strike are amplified by a factor of 2.5 from 0.3 to 1.0 Hz and those to the southeast are amplified by a factor of 1.6 from 0.3 to 0.7 Hz. We group the stations in NEHRP site classes, using average 1-D velocity structures to estimate site amplification as a function of frequency and assuming 0.40 ??? ?? ??? 0.55 sec for the near-surface attenuation. We increase the amplification of the soft-soil sites from 0.1 to 1.0 Hz by a factor that reaches 1.7 at 0.3 Hz because they are more strongly amplified than the NEHRP-D velocity structure predicts. We combine the 65 single-station estimates of radiated energy using an equal-azimuth weighting scheme that compensates for station distribution and incorporates the observed directivity, yielding a regional estimate of Es = 3.4 ?? 0.7 ?? 1022 dyne cm. This regional estimate of radiated energy corresponds closely to the teleseismic estimate of Es = 3.2 ?? 1022 dyne cm.

Preliminary radiationdoses were estimated and reported during Phase I of the Hanford Environmental Dose Reconstruction (HEDR) Project. As the project has progressed, additional information regarding the magnitude and timing of past radioactive releases has been developed, and the general scope of the required calculations has been enhanced. The overall HEDR computational model for computing doses attributable to atmospheric releases from Hanford Site operations is called HEDRIC (Hanford Environmental Dose Reconstruction Integrated Codes). It consists of four interrelated models: source term, atmospheric transport, environmental accumulation, and individual dose. The source term and atmospheric transport models are documented elsewhere. This report describes the initial implementation of the design specifications for the environmental accumulation model and computer code, called DESCARTES (Dynamic EStimates of Concentrations and Accumulated Radionuclides in Terrestrial Environments), and the individual dose model and computer code, called CIDER (Calculation of Individual Doses from Environmental Radionuclides). The computations required of these models and the design specifications for their codes were documented in Napier et al. (1992). Revisions to the original specifications and the basis for modeling decisions are explained. This report is not the final code documentation but gives the status of the model and code development to date. Final code documentation is scheduled to be completed in FY 1994 following additional code upgrades and refinements. The user's guide included in this report describes the operation of the environmental accumulation and individual dose codes and associated pre- and post-processor programs. A programmer's guide describes the logical structure of the programs and their input and output files.

Radiationdoses to individuals were estimated for the years 1944-1992 as part of the Hanford Dose Reconstruction Project (HEDR). The doseestimates were based on the radioactive releases to the atmosphere and Columbia River from the Hanford Site in southcentral Washington State. Conceptual models, computer codes, and previously published doseestimates were used to reconstruct doses. The most significant exposure pathway was found to be the consumption of cow`s milk containing {sup 131}I. The median cumulative doseestimates to the thyroid of children ranged from <0.7 mGy to 2.3 Gy throughout the study area, depending upon residence location. The highest estimated cumulative dose to a child ranged from 0.6-8.4 Gy (5th and 95th percentiles) with a median of 2.3 Gy based on 100 Monte Carlo realizations. The geographic distribution of the dose levels was directly related to the pattern of {sup 131}I deposition and was affected by the distribution of commercial milk and leafy vegetables. For the atmospheric pathway, the highest cumulative effective dose equivalent to an adult was estimated to be 12 mSv at Ringold, Washington, for the period 1944-1992. For the Columbia River pathway, cumulative effective dose equivalent estimates ranged from <5 mSv to 15 mSv cumulative dose to maximally exposed adults downriver from the Hanford Site for the years 1944-1992. The most significant river exposure pathway was consumption of resident fish containing {sup 32}P and {sup 65}Zn.

Endodontic patients are sometimes concerned about the risks of tumors or cataracts from radiation exposure during root canal therapy. By using established dose and risk information, we calculated the extent of these risks. The chance of getting leukemia from an endodontic x-ray survey using 90 kVp was found to be 1 in 7.69 million, the same as the risk of dying from cancer from smoking 0.94 cigarettes or from an auto accident when driving 3.7 km. Risk of thyroid gland neoplasia was 1 in 667,000 (smoking 11.6 cigarettes, driving 45 km) and risk of salivary gland neoplasia 1 in 1.35 million (smoking 5.4 cigarettes, driving 21.1 km). Use of 70 kVp radiography reduced these risks only slightly. To receive the threshold dose to eyes to produce cataract changes, a patient would have to undergo 10,900 endodontic surveys. PMID:2390963

Radionuclide myocardial perfusion imaging (MPI) plays a vital role in the evaluation and management of patients with coronary artery disease. However, because of a steep growth in MPI in the mid 2000s, concerns about inappropriate use of MPI and imaging-related radiation exposure increased. In response, the professional societies developed appropriate-use criteria for MPI. Simultaneously, novel technology, image-reconstruction software for traditional scanners, and dedicated cardiac scanners emerged and facilitated the performance of MPI with low-dose and ultra-low-dose radiotracers. This paper provides a practical approach to performing low-radiation-dose MPI using traditional and novel technologies. PMID:25766891

Across the globe nuclear utilities are in the process of designing and analysing Independent Spent Fuel Storage Installations (ISFSI) for the purpose of above ground spent-fuel storage primarily to mitigate the filling of spent-fuel pools. Using a conjoining of discrete ordinates transport theory (DORT) and Monte Carlo (MCNP) techniques, an ISFSI was analysed to determine neutron and photon dose rates for a generic overpack, and ISFSI pad configuration and design at distances ranging from 1 to -1700 m from the ISFSI array. The calculated dose rates are used to address the requirements of 10CFR72.104, which provides limits to be enforced for the protection of the public by the NRC in regard to ISFSI facilities. For this overpack, dose rates decrease by three orders of magnitude through the first 200 m moving away from the ISFSI. In addition, the contributions from different source terms changes over distance. It can be observed that although side photons provide the majority of dose rate in this calculation, scattered photons and side neutrons take on more importance as the distance from the ISFSI is increased. PMID:16604670

The increased occupational doses resulting from the Chernobyl nuclear reactor accident that occurred in Ukraine in April 1986, the reactor accident of Fukushima that took place in Japan in March 2011, and the early operations of the Mayak Production Association in Russia in the 1940s and 1950s are presented and discussed. For comparison purposes, the occupational doses due to the other two major reactor accidents (Windscale in the United Kingdom in 1957 and Three Mile Island in the United States in 1979) and to the main plutonium-producing facility in the United States (Hanford Works) are also covered but in less detail. Both for the Chernobyl nuclear reactor accident and the routine operations at Mayak, the considerable efforts made to reconstruct individual doses from external irradiation to a large number of workers revealed that the recorded doses had been overestimated by a factor of about two.Introduction of Increased Occupational Exposures: Nuclear Industry Workers. (Video 1:32, http://links.lww.com/HP/A21). PMID:24378501

A patient with malignant melanoma was treated by thermal neutron capture therapy using 10B-paraboronophenylalanine. The compound was injected subcutaneously into ten locations in the tumor-surrounding skin, and the patient was then irradiated with thermal neutrons from the Musashi Reactor at reactor power of 100 KW and neutron flux of 1.2 X 10(9) n/cm{sup 2}/s. Total absorbed dose to the skin was 11.7-12.5 Gy in the radiation field. The dose equivalents of these doses were estimated as 21.5 and 24.4 Sv, respectively. Early skin reaction after irradiation was checked from day 1 to day 60. The maximum and mean skin scores were 2.0 and 1.5, respectively, and the therapy was safely completed as far as skin reaction was concerned. Some factors influencing the absorbed dose and dose equivalent to the skin are discussed.

Exposure to radiation as a result of medical imaging is currently in the spotlight, receiving attention from Congress as well as the lay press. Although scanner manufacturers are moving toward including effective dose information in the Digital Imaging and Communications in Medicine headers of imaging studies, there is a vast repository of retrospective CT data at every imaging center that stores dose information in an image-based dose sheet. As such, it is difficult for imaging centers to participate in the ACR's Dose Index Registry. The authors have designed an automated extraction system to query their PACS archive and parse CT examinations to extract the dose information stored in each dose sheet. First, an open-source optical character recognition program processes each dose sheet and converts the information to American Standard Code for Information Interchange (ASCII) text. Each text file is parsed, and radiationdose information is extracted and stored in a database which can be queried using an existing pathology and radiology enterprise search tool. Using this automated extraction pipeline, it is possible to perform dose analysis on the >800,000 CT examinations in the PACS archive and generate dose reports for all of these patients. It is also possible to more effectively educate technologists, radiologists, and referring physicians about exposure to radiation from CT by generating report cards for interpreted and performed studies. The automated extraction pipeline enables compliance with the ACR's reporting guidelines and greater awareness of radiationdose to patients, thus resulting in improved patient care and management. PMID:21040869

In this work we quantified the effective UV radiationdose in orange and colorless polyethylene samples exposed to weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral distribution of solar radiation, although the chemical structure of materials is also important.

The United States conducted atmospheric testing of nuclear devices at the Nevada Test Site from 1951 through 1963. In 1979 the U.S. Department of Energy established the Off-Site Radiation Exposure Review Project to compile a data base related to health effects from nuclear testing and to reconstruct doses to public residing off of the Nevada Test Site. This project is the most comprehensive dose reconstruction project to date, and, since similar assessments are currently underway at several other locations within and outside the U.S., lessons from ORERP can be valuable. A major component of dose reconstruction is estimation of dose from radionuclide ingestion. The PATHWAY food-chain model was developed to estimate the amount of radionuclides ingested. For agricultural components of the human diet, PATHWAY predicts radionuclide concentrations and quantities ingested. To improve accuracy and model credibility, four components of model analysis were conducted: estimation of uncertainty in model predictions, estimation of sensitivity of model predictions to input parameters, and testing of model predictions against independent data (validation), and comparing predictions from PATHWAY with those from other models. These results identified strengths and weaknesses in the model and aided in establishing the confidence associated with model prediction, which is a critical component risk assessment and dose reconstruction. For fallout from the Nevada Test Site, by far, the largest internal doses were received by the thyroid. However, the predicted number of fatal cancers from ingestion dose was generally much smaller than the number predicted from external dose. The number of fatal cancers predicted from ingestion dose was also orders of magnitude below the normal projected cancer rate. Several lessons were learned during the study that are relevant to other dose reconstruction efforts.

A questionnaire was developed by the members of WG12 of EURADOS in order to establish an overview of the current status of eye lens radiationdose monitoring in hospitals. The questionnaire was sent to medical physicists and radiation protection officers in hospitals across Europe. Specific topics were addressed in the questionnaire such as: knowledge of the proposed eye lens dose limit; monitoring and dosimetry issues; training and radiation protection measures. The results of the survey highlighted that the new eye lens dose limit can be exceeded in interventional radiology procedures and that eye lens protection is crucial. Personnel should be properly trained in how to use protective equipment in order to keep eye lens doses as low as reasonably achievable. Finally, the results also highlighted the need to improve the design of eye dosemeters in order to ensure satisfactory use by workers. PMID:25222935

Purpose: To develop a method to quantify the therapeutic effect of radiosensitization by hyperthermia; to this end, a numerical method was proposed to convert radiation therapy dose distributions with hyperthermia to equivalent dose distributions without hyperthermia. Methods and Materials: Clinical intensity modulated radiation therapy plans were created for 15 prostate cancer cases. To simulate a clinically relevant heterogeneous temperature distribution, hyperthermia treatment planning was performed for heating with the AMC-8 system. The temperature-dependent parameters α (Gy{sup −1}) and β (Gy{sup −2}) of the linear–quadratic model for prostate cancer were estimated from the literature. No thermal enhancement was assumed for normal tissue. The intensity modulated radiation therapy plans and temperature distributions were exported to our in-house-developed radiation therapy treatment planning system, APlan, and equivalent dose distributions without hyperthermia were calculated voxel by voxel using the linear–quadratic model. Results: The planned average tumor temperatures T90, T50, and T10 in the planning target volume were 40.5°C, 41.6°C, and 42.4°C, respectively. The planned minimum, mean, and maximum radiation therapy doses were 62.9 Gy, 76.0 Gy, and 81.0 Gy, respectively. Adding hyperthermia yielded an equivalent dose distribution with an extended 95% isodose level. The equivalent minimum, mean, and maximum doses reflecting the radiosensitization by hyperthermia were 70.3 Gy, 86.3 Gy, and 93.6 Gy, respectively, for a linear increase of α with temperature. This can be considered similar to a dose escalation with a substantial increase in tumor control probability for high-risk prostate carcinoma. Conclusion: A model to quantify the effect of combined radiation therapy and hyperthermia in terms of equivalent dose distributions was presented. This model is particularly instructive to estimate the potential effects of interaction from different

The low energy component of the cosmic radiation field is strongly modified by the shielding of the spacecraft and it is time and location dependent. Thermoluminescent lithium fluoride detectors have been applied to determine the radiationdoses inside the ESA-Facility BIOPAN. The BIOPAN facility was mounted outside and launched on a Foton spacecraft and opened to space to allow exposure of several experiments to open space. Standard TLD-600. TLD-700 chips, two layers MTS-Ns sintered pellets with different effective thickness of the sensitive layer and MTS-N of different thickness have been exposed with different shielding thicknesses in front of them. The measured TL signal in the 0.1 mm thick detector just shielded by an aluminised Kapton foil of 25 microm thickness in front yielded a dose of 29.8 Gy (calibrated with 137Cs gamma rays) for an exposure time of 12.7 days: after 2.5 g.cm(-2) shielding the doses dropped to 3 mGy. The monitoring of radiationdoses and its depth dose distribution outside the spacecraft are of great interest for radiation protection of astronauts working in open space. The knowledge of depth-dose distribution is a prerequisite to determine the organ doses an astronaut will receive during an extravehicular activity (EVA). The BIOPAN experiments are to be continued in the future. PMID:12382937

This work presents initial data on radiationdoses in adult computed tomography (CT) in Serbia. Data were collected in terms of CT dose index (CTDIvol) and dose length product (DLP) values for head, chest and abdomen examination. The range of CTDIvol values was found to be 53-98, 11-34 and 8.5-227 mGy whereas for DLP was 803-1066, 350-845 and 1066-3078 mGy cm(-1) for head, chest and abdomen examination, respectively. Except for abdomen on one CT unit, all estimated values were in line with the reported data. This work also presents simple method on how to reduce radiationdoses when scanning head. Using axial (step-and-shot) instead of helical mode and decreasing tube current-time product leads to significant dose reduction. CTDIvol was decreased by 20 % whereas DLP was reduced for a factor 2. PMID:25063787

Radiation therapy is an integral part of cancer treatment, but to date it remains highly manual. Plans are created through optimization of dose volume objectives that specify intent to minimize, maximize, or achieve a prescribed dose level to clinical targets and organs. Optimization is NP-hard, requiring highly iterative and manual initialization procedures. We present a proof-of-concept for a method to automatically infer the radiationdose directly from the patient's treatment planning image based on a database of previous patients with corresponding clinical treatment plans. Our method uses regression forests augmented with density estimation over the most informative features to learn an automatic atlas-selection metric that is tailored to dose prediction. We validate our approach on 276 patients from 3 clinical treatment plan sites (whole breast, breast cavity, and prostate), with an overall dose prediction accuracies of 78.68%, 64.76%, 86.83% under the Gamma metric. PMID:26660888

Dose reconstruction for studies of the health effects of ionizing radiation have been carried out for many decades. Major studies have included Japanese bomb survivors, atomic veterans, downwinders of the Nevada Test Site and Hanford, underground uranium miners, and populations of nuclear workers. For such studies to be credible, significant effort must be put into applying the best science to reconstructing unbiased absorbed doses to tissues and organs as a function of time. In many cases, more and more sophisticated dose reconstruction methods have been developed as studies progressed. For the example of the Japanese bomb survivors, the dose surrogate “distance from the hypocenter” was replaced by slant range, and then by TD65 doses, DS86 doses, and more recently DS02 doses. Over the years, it has become increasingly clear that an equal level of effort must be expended on the quantitative assessment of uncertainty in such doses, and to reducing and managing uncertainty. In this context, this paper reviews difficulties in terminology, explores the nature of Berkson and classical uncertainties in dose reconstruction through examples, and proposes a path forward for Joint Coordinating Committee for Radiation Effects Research (JCCRER) Project 2.4 that requires a reasonably small level of effort for DOSES-2008.

This report documents the RADTRAD computer code developed for the U.S. Nuclear Regulatory Commission (NRC) Office of Nuclear Reactor Regulation (NRR) to estimate transport and removal of radionuclides and dose at selected receptors. The document includes a users` guide to the code, a description of the technical basis for the code, the quality assurance and code acceptance testing documentation, and a programmers` guide. The RADTRAD code can be used to estimate the containment release using either the NRC TID-14844 or NUREG-1465 source terms and assumptions, or a user-specified table. In addition, the code can account for a reduction in the quantity of radioactive material due to containment sprays, natural deposition, filters, and other natural and engineered safety features. The RADTRAD code uses a combination of tables and/or numerical models of source term reduction phenomena to determine the time-dependent dose at user-specified locations for a given accident scenario. The code system also provides the inventory, decay chain, and dose conversion factor tables needed for the dose calculation. The RADTRAD code can be used to assess occupational radiation exposures, typically in the control room; to estimate site boundary doses; and to estimatedose attenuation due to modification of a facility or accident sequence.

Settlements near the Semipalatinsk Test Site (SNTS) in northeastern Kazakhstan were exposed to radioactive fallout during 1949–1962. Thyroid disease prevalence among 2994 residents of eight villages was ascertained by ultrasound screening. Malignancy was determined by cytopathology. Individual thyroid doses from external and internal radiation sources were reconstructed from fallout deposition patterns, residential histories and diet, including childhood milk consumption. Point estimates of individual external and internal dose averaged 0.04 Gy (range 0–0.65) and 0.31 Gy (0–9.6), respectively, with a Pearson correlation coefficient of 0.46. Ultrasound-detected thyroid nodule prevalence was 18% and 39% among males and females, respectively. It was significantly and independently associated with both external and internal dose, the main study finding. The estimated relative biological effectiveness of internal compared to external radiationdose was 0.33, with 95% confidence bounds of 0.09–3.11. Prevalence of papillary cancer was 0.9% and was not significantly associated with radiationdose. In terms of excess relative risk per unit dose, our dose–response findings for nodule prevalence are comparable to those from populations exposed to medical X rays and to acute radiation from the Hiroshima and Nagasaki atomic bombings. PMID:18363427

The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

Purpose: Estimation of Cerenkov dose from high-energy megavoltage photon and electron beams in tissue and its impact on the radiosensitization using Protoporphyrine IX (PpIX) for tumor targeting enhancement in radiotherapy. Methods: The GEPTS Monte Carlo code is used to generate dose distributions from 18MV Varian photon beam and generic high-energy (45-MV) photon and (45-MeV) electron beams in a voxel-based tissueequivalent phantom. In addition to calculating the ionization dose, the code scores Cerenkov energy released in the wavelength range 375–425 nm corresponding to the pick of the PpIX absorption spectrum (Fig. 1) using the Frank-Tamm formula. Results: The simulations shows that the produced Cerenkov dose suitable for activating PpIX is 4000 to 5500 times lower than the overall radiationdose for all considered beams (18MV, 45 MV and 45 MeV). These results were contradictory to the recent experimental studies by Axelsson et al. (Med. Phys. 38 (2011) p 4127), where Cerenkov dose was reported to be only two orders of magnitude lower than the radiationdose. Note that our simulation results can be corroborated by a simple model where the Frank and Tamm formula is applied for electrons with 2 MeV/cm stopping power generating Cerenkov photons in the 375–425 nm range and assuming these photons have less than 1mm penetration in tissue. Conclusion: The Cerenkov dose generated by high-energy photon and electron beams may produce minimal clinical effect in comparison with the photon fluence (or dose) commonly used for photo-dynamic therapy. At the present time, it is unclear whether Cerenkov radiation is a significant contributor to the recently observed tumor regression for patients receiving radiotherapy and PpIX versus patients receiving radiotherapy only. The ongoing study will include animal experimentation and investigation of dose rate effects on PpIX response.

The use of noncoplanar intensity-modulated radiation therapy (IMRT) might result in better sparing of some critical organs because of a higher degree of freedom in beam angle optimization. However, this can lead to a potential increase in peripheral dose compared with coplanar IMRT. The peripheral dose from noncoplanar IMRT has not been previously quantified. This study examines the peripheral dose from noncoplanar IMRT compared with coplanar IMRT for pediatric radiation therapy. Five cases with different pediatric malignancies in head and neck were planned with both coplanar and noncoplanar IMRT techniques. The plans were performed such that the tumor coverage, conformality, and dose uniformity were comparable for both techniques. To measure the peripheral doses of the 2 techniques, thermoluminescent dosimeters (TLD) were placed in 10 different organs of a 5-year-old pediatric anthropomorphic phantom. With the use of noncoplanar beams, the peripheral doses to the spinal cord, bone marrow, lung, and breast were found to be 1.8-2.5 times of those using the coplanar technique. This is mainly because of the additional internal scatter dose from the noncoplanar beams. Although the use of noncoplanar technique can result in better sparing of certain organs such as the optic nerves, lens, or inner ears depending on how the beam angles were optimized on each patient, oncologists should be alert of the possibility of significantly increasing the peripheral doses to certain radiation-sensitive organs such as bone marrow and breast. This might increase the secondary cancer risk to patients at young age.

The focus of the work of Committee 2 of the International Commission on Radiological Protection (ICRP) is the computation of dose coefficients compliant with Publication 103 A set of reference computational phantoms is being developed, based on medical imaging data, and used for radiation transport calculations. Biokinetic models used to describe the behaviour of radionuclides in body tissues are being updated, also leading to changes in organ doses and effective dose coefficients. Dose coefficients for external radiation exposure of adults calculated using the new reference phantoms were issued as Publication 116, jointly with the International Commission on Radiation Units and Measurements. Forthcoming reports will provide internal dose coefficients for radionuclide inhalation and ingestion by workers, and associated bioassay data. Work is in progress to revise internal dose coefficients for members of the public, and, for the first time, to provide reference values for external exposures of the public. Committee 2 is also working with Committee 3 on dose coefficients for radiopharmaceuticals, and leading a cross-Committee initiative to give advice on the use of effective dose. PMID:26984902

Space radiation is one of the main concerns in planning long-term interplanetary human space missions. There are two main types of hazardous radiation - Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR). Their intensities and evolution depend on the solar activity. GCR activity is most enhanced during solar minimum, while the most intense SEPs usually occur during the solar maximum. SEPs are better shielded with thick shields, while GCR dose is less behind think shields. Time and thickness dependences of the intensity of these two components encourage looking for a time window of flight, when radiation intensity and dose of SEP and GCR would be minimized. In this study we combine state-of-the-art space environment models with GEANT4 simulations to determine the optimal shielding, geometry of the spacecraft, and launch time with respect to the phase of the solar cycle. The radiation environment was described by the time-dependent GCR model, and the SEP spectra that were measured during the period from 1990 to 2010. We included gamma rays, electrons, neutrons and 27 fully ionized elements from hydrogen to nickel. We calculated the astronaut's radiationdoses during interplanetary flights using the Monte-Carlo code that accounts for the primary and the secondary radiation. We also performed sensitivity simulations for the assumed spacecraft size and thickness to find an optimal shielding. In conclusion, we present the dependences of the radiationdose as a function of launch date from 1990 to 2010, for flight durations of up to 3 years.

In radiation accidents, determining the radiationdose the victim received is a key step for medical decision making and patient prognosis. To reconstruct and evaluate the absorbed dose, researchers have developed many physical devices and biological techniques during the last decades. However, using the physical parameter "absorbed dose" alone is not sufficient to predict the clinical development of the various organs injured in an individual patient. In operational situations for radiation accidents, medical responders need more urgently to classify the severity of the radiation injury based on the signs and symptoms of the patient. In this work, the author uses a unified hematopoietic model to describe dose-dependent dynamics of granulocytes, lymphocytes, and platelets, and the corresponding clinical grading of hematopoietic acute radiation syndrome. This approach not only visualizes the time course of the patient's probable outcome in the form of graphs but also indirectly gives information of the remaining stem and progenitor cells, which are responsible for the autologous recovery of the hematopoietic system. Because critical information on the patient's clinical evolution can be provided within a short time after exposure and only peripheral cell counts are required for the simulation, these modeling tools will be useful to assess radiation exposure and injury in human-involved radiation accident/incident scenarios. PMID:27575346

Allowing for imprecision of radiationdoseestimates for A-bomb survivors followed up by the Radiation Effects Research Foundation can be improved through recent statistical methodology. Since the entire RERF dosimetry system has recently been revised, it is timely to reconsider this. We have found that the dosimetry revision itself does not warrant changes in these methods but that the new methodology does. In addition to assumptions regarding the form and magnitude of doseestimation errors, previous and current methods involve the apparent distribution of true doses in the cohort. New formulas give results conveniently and explicitly in terms of these inputs. Further, it is now possible to use assumptions about two components of the dose errors, referred to in the statistical literature as "classical" and "Berkson-type". There are indirect statistical indications, involving non-cancer biological effects, that errors may be somewhat larger than assumed before, in line with recommendations made here. Inevitably, methods must rely on uncertain assumptions about the magnitude of dose errors, and it is comforting to find that, within the range of plausibility, eventual cancer risk estimates are not very sensitive to these. PMID:18582151

Advances in radiation treatment delivery, such as intensity modulated radiation therapy (IMRT), have made it possible to deliver large doses of radiation with a high degree of conformity. While highly conformal treatments offers the advantage of sparing surrounding normal tissue, this benefit can only be realized if the patient is accurately positioned during each treatment fraction. The need to accurately position the patient has led to the development and use of gantry mounted kilovoltage cone-beam computed tomography (kV-CBCT) systems. These systems are used to acquire high resolution volumetric images of the patient which are then digitally registered with the planning CT dataset to confirm alignment of the patient on the treatment table. While kV-CBCT is a very useful tool for aligning the patient prior to treatment, daily use in a high fraction therapy regimen results in a substantial radiationdose. In order to quantify the radiationdose associated with CBCT imaging, an anthropomorphic phantom representing a 50th percentile adult male and a fiber-optic coupled (FOC) dosimetry system were both constructed as part of this dissertation. These tools were then used to directly measure organ doses incurred during clinical protocols for the head, chest, and pelvis. For completeness, the dose delivered from both the X-ray Volumetric Imager (XVI, Elekta Oncology Systems, Crawley, UK) and the On-Board Imager (OBI, Varian Medical Systems, Palo Alto, CA) were investigated. While this study provided a direct measure of organ doses for estimating risk to the patient, a practical method for estimating organ doses that could be performed with phantoms and dosimeters currently available at most clinics was also desired. To accomplish this goal, a 100 mm pencil ion chamber was used to measure the "cone beam dose index" (CBDI) inside standard CT dose index (CTDI) acrylic phantoms. A weighted CBDI (CBDIw), similar to the weighted CT dose index (CTDIw), was then calculated to

Proton therapy reduces the integral therapeutic dose required for local control in prostate patients compared to intensity-modulated radiotherapy. One proposed benefit of this reduction is an associated decrease in the incidence of radiogenic secondary cancers. However, patients are also exposed to stray radiation during the course of treatment. The purpose of this study was to quantify the stray radiationdose received by patients during proton therapy for prostate cancer. Using a Monte Carlo model of a proton therapy nozzle and a computerized anthropomorphic phantom, we determined that the effective dose from stray radiation per therapeutic dose (E/D) for a typical prostate patient was approximately 5.5 mSv Gy-1. Sensitivity analysis revealed that E/D varied by ±30% over the interval of treatment parameter values used for proton therapy of the prostate. Equivalent doses per therapeutic dose (HT/D) in specific organs at risk were found to decrease with distance from the isocenter, with a maximum of 12 mSv Gy-1 in the organ closest to the treatment volume (bladder) and 1.9 mSv Gy-1 in the furthest (esophagus). Neutrons created in the nozzle predominated effective dose, though neutrons created in the patient contributed substantially to the equivalent dose in organs near the proton field. Photons contributed less than 15% to equivalent doses.

Objectives To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental, occupational, and medical diagnostic exposures. Design Multinational retrospective cohort study of cancer mortality. Setting Cohorts of workers in the nuclear industry in 15 countries. Participants 407 391 workers individually monitored for external radiation with a total follow-up of 5.2 million person years. Main outcome measurements Estimates of excess relative risks per sievert (Sv) of radiationdose for mortality from cancers other than leukaemia and from leukaemia excluding chronic lymphocytic leukaemia, the main causes of death considered by radiation protection authorities. Results The excess relative risk for cancers other than leukaemia was 0.97 per Sv, 95% confidence interval 0.14 to 1.97. Analyses of causes of death related or unrelated to smoking indicate that, although confounding by smoking may be present, it is unlikely to explain all of this increased risk. The excess relative risk for leukaemia excluding chronic lymphocytic leukaemia was 1.93 per Sv (< 0 to 8.47). On the basis of these estimates, 1-2% of deaths from cancer among workers in this cohort may be attributable to radiation. Conclusions These estimates, from the largest study of nuclear workers ever conducted, are higher than, but statistically compatible with, the risk estimates used for current radiation protection standards. The results suggest that there is a small excess risk of cancer, even at the low doses and dose rates typically received by nuclear workers in this study. PMID:15987704

Context More than 400 000 workers annually receive a measurable radiationdose and may be at increased risk of radiation-induced leukaemia. It is unclear whether leukaemia risk is elevated with protracted, low-dose exposure. Objective We conducted a meta-analysis examining the relationship between protracted low-dose ionising radiation exposure and leukaemia. Data sources Reviews by the National Academies and United Nations provided a summary of informative studies published before 2005. PubMed and Embase databases were searched for additional occupational and environmental studies published between 2005 and 2009. Study selection We selected 23 studies that: (1) examined the association between protracted exposures to ionising radiation and leukaemia excluding chronic lymphocytic subtype; (2) were a cohort or nested case–control design without major bias; (3) reported quantitative estimates of exposure; and (4) conducted exposure–response analyses using relative or excess RR per unit exposure. Methods Studies were further screened to reduce information overlap. Random effects models were developed to summarise between-study variance and obtain an aggregate estimate of the excess RR at 100 mGy. Publication bias was assessed by trim and fill and Rosenthal's file drawer methods. Results We found an ERR at 100 mGy of 0.19 (95% CI 0.07 to 0.32) by modelling results from 10 studies and adjusting for publication bias. Between-study variance was not evident (p=0.99). Conclusions Protracted exposure to low-dose gamma radiation is significantly associated with leukaemia. Our estimate agreed well with the leukaemia risk observed among exposed adults in the Life Span Study (LSS) of atomic bomb survivors, providing increased confidence in the current understanding of leukaemia risk from ionising radiation. However, unlike the estimates obtained from the LSS, our model provides a precise, quantitative summary of the direct estimates of excess risk from studies of

Epidemiologic studies of workers exposed occupationally to protracted low doses of radiation provide a direct assessment of health effects resulting from such exposure and thus supplement information provided by studies of populations exposed at high doses of radiation and high dose rates. Analyses based on combined data from several studies can be expected to provide a more thorough assessment of low dose occupational studies and more precise risk estimates than can be obtained from any single study. Statistical methods for conducting such combined analyses are discussed, and different approaches, such as basing analyses on various levels of aggregation of exposure data, are compared and evaluated. Emphasis is given to methods for obtaining risk estimates and confidence limits that can be appropriately compared with estimates that form the basis for current radiation protection standards; these estimates have been obtained through extrapolation from high dose data. Methods are illustrated using combined data on workers at three US Department of Energy facilities: the Hanford Site, Richland, Washington; the Oak Ridge National Laboratory, Oak Ridge, Tennessee; and the Rocky Flats Nuclear Weapons Plant, Denver, Colorado. PMID:2321632

Background Use of computed tomography (CT) for diagnostic evaluation has increased dramatically over the past two decades. Even though CT is associated with substantially higher radiation exposure than conventional x-rays, typical clinical doses are not known. We sought to estimate the radiationdose associated with common CT studies in clinical practice; assess variation in dose across types of studies, patients, and institutions; and quantify the potential cancer risk associated with these examinations. Methods Retrospective cross-sectional study describing radiationdose associated with the 11 most common types of diagnostic CT studies performed on 1,119 consecutive adult patients at four San Francisco Bay Area institutions between January 1 and May 30, 2008. We estimated lifetime attributable risks of cancer by study type from these measured doses. Results Radiationdoses varied significantly between the different types of CT studies. The overall median effective doses ranged from 2.1 milli-Sieverts (mSv) for a routine head CT (interquartile range [IQR] 1.8–2.8) to 31 mSv (IQR 21–43) for a multiphase abdomen and pelvis CT. Within each type of CT study, effective dose varied significantly within and across institutions, with a mean 13-fold variation between the highest and lowest dose for each study type. The estimated number of CTs that will lead to the development of a cancer varied widely depending on the specific type of CT examination and the patient’s age and sex. An estimated 1 in 270 women who underwent a coronary angiography CT at age 40 will develop cancer from that CT (1 in 600 men), compared with an estimated 1 in 8,100 women who had routine head CT at the same age (1 in 11, 080 men). For 20-year olds the risks were approximately doubled, and for 60-year olds, the risks were approximately 50% lower. Conclusion Radiationdoses from commonly performed diagnostic CT examinations were higher and more variable than generally quoted, highlighting the

The report presents specific and practical recommendations for whether, when, and how dose-reconstruction studies should be conducted, with an emphasis on public participation. The book provides an overview of the basic requirements and technical aspects of dose reconstruction; presents lessons to be learned from dose reconstructions after Chernobyl, Three Mile Island, and elsewhere; explores the potential benefits and limitations of using current available biological markers; discusses how to establish the source term determining what was released; explores methods for identifying the environmental pathways by which radiation reaches the body; offers details on three major categories of dose assessment; and examines priority-setting and strengths and limitations of epidemiological studies.

The effort to estimate the radiationdose received by an occupationally exposed worker is a complex task. Regulatory guidance assumes that the stochastic risks from uniform and non-uniform whole-body irradiations are equal. An ideal uniform irradiation of the whole body would require a broad parallel radiation field of relatively high-energy radiation, which many occupationally exposed workers do not experience. In reality, workers are exposed to a non-uniform irradiation of the whole body such as a radiation field with one or more types of radiation, each with varying energies and/or fluence rates, incident on the worker. Most occupational radiation exposure at LANL is due to neutron radiation. Many of these exposures originate from activities performed in glove boxes with nuclear materials. A standard Los Alamos 2 x 2 x 2 glove box is modeled with the source material being clean weapons grade plutonium. Dosimeter tally planes were modeled to stimulate the various positions that a dosimeter can be worn. An anthropomorphic phantom was used to determine whole body dose. Various geometries of source position and phantom location were used to determine the effects of streaming on the radiationdose a worker may receive. Based on computational and experimental results, the effects of a non-uniform radiation field have on radiationdose received by a worker in a glove box environment are: (1) Dosimeter worn at chest level can overestimate the whole body dose between a factor of two to six depending on location of the phantom with the source material close to the front of the glove box, (2) Dosimeter should be worn at waist level instead of chest level to more accurately reflect the whole body dose received, (3) Dose can be significantly higher for specific locations of the worker relative to the position of the source, (4) On the average the testes contribute almost 44% of the whole body dose for a male, and (5) Appropriate design considerations such as more shielding

Purpose: To demonstrate a radiationdose response and to determine the dosimetric and chemotherapeutic factors that influence the incidence of late renal toxicity following total body irradiation (TBI). Methods and Materials: A comprehensive retrospective review was performed of articles reporting late renal toxicity, along with renal dose, fractionation, dose rate, chemotherapy regimens, and potential nephrotoxic agents. In the final analysis, 12 articles (n = 1,108 patients), consisting of 24 distinct TBI/chemotherapy conditioning regimens were included. Regimens were divided into three subgroups: adults (age {>=}18 years), children (age <18 years), and mixed population (both adults and children). Multivariate logistic regression was performed to identify dosimetric and chemotherapeutic factors significantly associated with late renal complications. Results: Individual analysis was performed on each population subgroup. For the purely adult population, the only significant variable was total dose. For the mixed population, the significant variables included total dose, dose rate, and the use of fludarabine. For the pediatric population, only the use of cyclosporin or teniposide was significant; no dose response was noted. A logistic model was generated with the exclusion of the pediatric population because of its lack of dose response. This model yielded the following significant variables: total dose, dose rate, and number of fractions. Conclusion: A dose response for renal damage after TBI was identified. Fractionation and low dose rates are factors to consider when delivering TBI to patients undergoing bone marrow transplantation. Drug therapy also has a major impact on kidney function and can modify the dose-response function.

It is well established that high-dose ionising radiation causes cardiovascular diseases. In contrast, the evidence for a causal relationship between long-term risk of cardiovascular diseases after moderate doses (0.5-5 Gy) is suggestive and weak after low doses (<0.5 Gy). However, evidence is emerging that doses under 0.5 Gy may also increase long-term risk of cardiovascular disease. This would have major implications for radiation protection with respect to medical use of radiation for diagnostic purposes and occupational or environmental radiation exposure. Therefore, it is of great importance to gain information about the presence and possible magnitude of radiation-related cardiovascular disease risk at doses of less than 0.5 Gy. The biological mechanisms implicated in any such effects are unclear and results from epidemiological studies are inconsistent. Molecular epidemiological studies can improve the understanding of the pathogenesis and the risk estimation of radiation-induced circulatory disease at low doses. Within the European DoReMi (Low Dose Research towards Multidisciplinary Integration) project, strategies to conduct molecular epidemiological studies in this field have been developed and evaluated. Key potentially useful European cohorts are the Mayak workers, other nuclear workers, uranium miners, Chernobyl liquidators, the Techa river residents and several diagnostic or low-dose radiotherapy patient cohorts. Criteria for informative studies are given and biomarkers to be investigated suggested. A close collaboration between epidemiology, biology and dosimetry is recommended, not only among experts in the radiation field, but also those in cardiovascular diseases. PMID:26041268

A new MIRD dynamic model has been used to provide estimates of the dose to the urinary bladder resulting from the administration of the therapeutic agents as iodide (for thyroid carcinoma) and meta-iodobenzylguanidine (MIBG) (for neuroendocrine tumours). Because the latter agent is used for therapeutic purposes in children, doseestimates were obtained for subjects aged 1 year and upwards. Those parameters likely to influence the bladder dose were also investigated, making use of the inherent flexibility of the model. For an administration of 1 GBq of either as iodide or MIBG to an adult subject, the radiationdose to the inner surface of the bladder was estimated to be approximately 1100 mGy, which is nearly twice the value estimated using a constant-volume bladder model. The new model produced doseestimates for children (within the range of MIBG) which were approximately 50% greater than those derived using a constant-volume bladder model. The urine flow rate was found to have the greatest effect on the bladder dose, a flow of twice the normal rate resulting in a reduction in the bladder dose by a factor of two. On the other hand, a reduction in the urine flow rate to half the normal value was estimated to increase the radiationdose by a factor of two. This was true for subjects of all ages. With normal voiding, the average dose to the bladder wall from -radiation was estimated to be 5 - 13% of the surface beta dose for

the earth. These particles come from the Van Allen Belt, Solar Cosmic Ray and Galaxy Cosmic Ray. They have different energy and flux, varying with time and space, and correlating with solar activity tightly. These particles interact with electrical components and materials used on satellites, producing various space radiation effects, which will damage satellite to some extent, or even affect its safety. orbit. Space energy particles inject into components and materials used on satellites, and generate radiationdose by depositing partial or entire energy in them through ionization, which causes their characteristic degradation or even failure. As a consequence, the analysis and protection for radiationdose has been paid more attention during satellite design and manufacture. Designers of satellites need to analyze accurately the space radiationdose while satellites are on orbit, and use the results as the basis for radiation protection designs and ground experiments for satellites. can be calculated, using the model of the trapped proton and the trapped electron in the Van Allen Belt (AE8 and AP8). This is the 1D radiationdose analysis for satellites. Obviously, the mass shielding from the outside space to the computed point in all directions is regarded as a simple sphere shell. The actual structure of satellites, however, is very complex. When energy particles are injecting into a given equipment inside satellite from outside space, they will travel across satellite structure, other equipment, the shell of the given equipment, and so on, which depends greatly on actual layout of satellite. This complex radiation shielding has two characteristics. One is that the shielding masses for the computed point are different in different injecting directions. The other is that for different computed points, the shielding conditions vary in all space directions. Therefore, it is very difficult to tell the differences described above using the 1D radiation analysis, and

To quantify the risk of radiation-induced leukemia and provide further information on the nature of the relationship between dose and response, a case-control study was undertaken in a cohort of over 150,000 women with invasive cancer of the uterine cervix. The cases either were reported to one of 17 population-based cancer registries or were treated in any of 16 oncologic clinics in Canada, Europe, and the United States. Four controls were individually matched to each of 195 cases of leukemia on the basis of age and calendar year when diagnosed with cervical cancer and survival time. Leukemia diagnoses were verified by one hematologist. Radiationdose to active bone marrow was estimated by medical physicists on the basis of the original radiotherapy records of study subjects. The risk of chronic lymphocytic leukemia, one of the few malignancies without evidence for an association with ionizing radiation, was not increased (relative risk (RR) = 1.03; n = 52). However, for all other forms of leukemia taken together (n = 143), a twofold risk was evident (RR = 2.0; 90% confidence interval = 1.0-4.2). Risk increased with increasing radiationdose until average doses of about 400 rad (4 Gy) were reached and then decreased at higher doses. This pattern is consistent with experimental data for which the down-turn in risk at high doses has been interpreted as due to killing of potentially leukemic cells. The dose-response information was modeled with various RR functions, accounting for the nonhomogeneous distribution of radiationdose during radiotherapy. The local radiationdoses to each of 14 bone marrow compartments for each patient were incorporated in the models, and the corresponding risks were summed.

the shape of the dose response to the reference radiation than it is on the radiation type of interest.A large study using micronuclei as biomarkers following exposure to different energies of mono-energetic neutrons, x-rays and gamma rays delivered at very low doses (0.0 to 0.10 Gy) is reported. As additional biomarkers of risk involved in critical steps in the carcinogenic process are developed, it may become possible to base risk estimates on biological change rather than the radiation energy deposition or dose.

Adults usually ask their physician about the kind of treatment they will be given and especially whether ionizing radiation applied for therapeutic purposes is harmful. When these treatments are applied to children and especially to infants of <18 months of age, parents should be more reluctant to give their consent for such a treatment. A paper under the title "Effect of low doses of ionizing radiation in infancy on cognitive function in adulthood: Swedish population based cohort study" written by Hall P, Adami HO, Trichopoulos D, et al. and published in the British Journal of Medicine 2004, 328:19-21 presents new and important data referring to 3094 males who at an age of <18 months had undergone radiation treatment for haemangiomas of the head and other dermatological lesions. The doses they received in their brain were from 20 mGy to > 250 mGy. Findings were exciting. 17%-32% of these infants did not attend highschool lessons. Many failed to pass tests related to cognitive tests for learning ability or logical reasoning. On the contrary spatial recognition was intact. As the authors state it is important to know that a cranial tomography examination administers to the brain of infants about 120 mGy. These doses are relevant to the doses tested above and found harmful. More radiation protection studies about the possible harmful effects on humans who receive doses of radiation for diagnostic and/or therapeutic purposes, are necessary. PMID:16868634

Purpose: To estimate organ and effective radiationdoses due to backscatter security scanners using Monte Carlo simulations and a voxelized phantom set. Methods: Voxelized phantoms of male and female adults and children were used with the GEANT4 toolkit to simulate a backscatter security scan. The backscatter system was modeled based on specifications available in the literature. The simulations modeled a 50 kVp spectrum with 1.0 mm-aluminum-equivalent filtration and a previously measured exposure of approximately 4.6 {mu}R at 30 cm from the source. Photons and secondary interactions were tracked from the source until they reached zero kinetic energy or exited from the simulation's boundaries. The energy deposited in the phantoms' respective organs was tallied and used to calculate total organ dose and total effective dose for frontal, rear, and full scans with subjects located 30 and 75 cm from the source. Results: For a full screen, all phantoms' total effective doses were below the established 0.25 {mu}Sv standard, with an estimated maximum total effective dose of 0.07 {mu}Sv for full screen of a male child. The estimated maximum organ dose due to a full screen was 1.03 {mu}Gy, deposited in the adipose tissue of the male child phantom when located 30 cm from the source. All organ doseestimates had a coefficient of variation of less than 3% for a frontal scan and less than 11% for a rear scan. Conclusions: Backscatter security scanners deposit dose in organs beyond the skin. The effective dose is below recommended standards set by the Health Physics Society (HPS) and the American National Standards Institute (ANSI) assuming the system provides a maximum exposure of approximately 4.6 {mu}R at 30 cm.

It is important that staff radiationdoses be kept 'as low as reasonably achievable' (ALARA). Staff working in the radiopharmacy and nursing staff responsible for injecting radionuclides are being monitored constantly in our department. We report here on the effective doses and doses to the hands received by staff at two hospitals during 8 years from January 1985 to December 1992. In addition to the doses determined monthly by the South African Bureau of Standards' Radiation Protection Service (SABS), radiationdoses received to the hands and whole body were measured every week using lithium fluoride thermoluminescent dosimetry (TLD). The workload (number of patient studies each year) and the estimated amount of 99Tcm received per month were also established, and results have been expressed in relation to these where possible. The combined radiationdoses and the absorbed dose per unit activity a single radiographer would have received, since 1988 when radiopharmacy duties were centralized, were calculated. The highest total radiationdose received in any one year by any one person at hospital A was 223.53 mSv to the hands, and 10.20 mSv and 8.37 mSv to the whole body depending on the dosimeter used. The corresponding values for hospital B were 54.05 mSv to the hands and 6.94 mSv and 4.43 mSv to the whole body. If only one radiographer should do all the work the calculated highest dose received would be 447.06 mSv to the hands and 9.68 mSv SABS effective dose.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8170638

Chang-hua Christian Hospital needs to uninstall the 60Co unit. The mode of this 60Co teletherapy unit is SHIMADZU RTGS-10. The original lead head was taken as the source container of this 60Co unit. The source head was dismantled and put into the prepared wooden box, after the source was sealed. This study describes the planning and dismantling of the retirement and transport of the 60Co unit, and personal doses measured during the procedure. This work estimates the doses of radiation received by exposed workers during the dismantling of the machine. The workers received doses of approximately 53 microSv. This study shows that the original lead head can be used as the source container of this 60Co unit. The 60Co machine was smoothly dismantled and transported by conscientious and careful workers, using planned and controlled radiation protection, following the ALARA (as low as reasonably achievable) rule. PMID:14653329

The analysis of chromosomal aberrations in peripheral blood of radiation accident victims is an established method of biological dosimetry. The doseestimate on the basis of an in vitro calibration curve is straightforward when the radiation exposure is homogeneous and the analysis not delayed. In recent years three radiation accidents occurred, where the irradiation or sampling conditions precluded a simple estimation of the dose. During the Georgian accident soldiers carried in their pockets small sources of 137Cs leading to partial and protracted body exposures. During the Tokai-mura accident, three employees involved in the process of 235U enrichment were exposed to very high doses of gamma rays and neutrons. During the Bialystok accident, five patients with breast cancer undergoing radiotherapy were exposed to a single dose of electrons which reached about 100 Gy. In the present paper the approaches chosen to estimate, by cytogenetic methods, the doses absorbed by the people involved in the accidents are described. PMID:15162038

Chromosome aberration frequency provides the most reliable biological marker of dose for detecting acute accidental radiation exposure. Significant radiation-induced changes in the frequency of chromosome aberrations can be detected at very low doses. Our paper provides information on using molecular chromosome probes ``paints`` to score chromosome damage and illustrates how technical advances make it possible to understand mechanisms involved during formation of chromosome aberrations. In animal studies chromosome aberrations provide a method to relate cellular damage to cellular dose. Using an In vivo/In vitro approach aberrations provided a biological marker of dose from radon progeny exposure which was used to convert WLM to dose in rat tracheal epithelial cells. Injection of Chinese hamsters with {sup 144}Ce which produced a low dose rate exposure of bone marrow to either low-LET radiation increased the sensitivity of the cells to subsequent external exposure to {sup 60}Co. These studies demonstrated the usefulness of chromosome damage as a biological marker of dose and cellular responsiveness.

Chromosome aberration frequency provides the most reliable biological marker of dose for detecting acute accidental radiation exposure. Significant radiation-induced changes in the frequency of chromosome aberrations can be detected at very low doses. Our paper provides information on using molecular chromosome probes paints'' to score chromosome damage and illustrates how technical advances make it possible to understand mechanisms involved during formation of chromosome aberrations. In animal studies chromosome aberrations provide a method to relate cellular damage to cellular dose. Using an In vivo/In vitro approach aberrations provided a biological marker of dose from radon progeny exposure which was used to convert WLM to dose in rat tracheal epithelial cells. Injection of Chinese hamsters with [sup 144]Ce which produced a low dose rate exposure of bone marrow to either low-LET radiation increased the sensitivity of the cells to subsequent external exposure to [sup 60]Co. These studies demonstrated the usefulness of chromosome damage as a biological marker of dose and cellular responsiveness.

It is generally considered that irradiated spent fuel is so radioactive (self-protecting) that it can only be moved and processed with specialized equipment and facilities. However, a small, possibly subnational, group acting in secret with no concern for the environment (other than the reduction of signatures) and willing to incur substantial but not lethal radiationdoses, could obtain plutonium by stealing and processing irradiated spent fuel that has cooled for several years. In this paper, we estimate the dose rate at various distances and directions from typical pressurized-water reactor (PWR) and boiling-water reactor (BWR) spent-fuel assemblies as a function of cooling time. Our results show that the dose rate is reduced rapidly for the first ten years after exposure in the reactor, and that it is reduced by a factor of {approx}10 (from the one year dose rate) after 15 years. Even for fuel that has cooled for 15 years, a lethal dose (LD50) of 450 rem would be received at 1 m from the center of the fuel assembly after several minutes. However, moving from 1 to 5 m reduces the dose rate by over a factor of 10, and moving from 1 to 10 m reduces the dose rate by about a factor of 50. The dose rates 1 m from the top or bottom of the assembly are considerably less (about 10 and 22%, respectively) than 1 m from the center of the assembly, which is the direction of the maximum dose rate.

Purpose: To develop a computed tomography (CT) organ doseestimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ doseestimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different

Purpose: To develop a computed tomography (CT) organ doseestimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantoms Methods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult male and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen∕pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen∕pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ doseestimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for

Exposure of the breast to ionising radiation increases the risk of breast cancer, especially among young women. However, some issues remain controversial, for instance the shape of the dose-response curve and the expression of time-related excess. The main purpose of this report was to examine the dose-response curves for radiation-induced breast cancer formulated according to radiobiological target theories. Another purpose was to analyse the time-related excess of breast cancer risk after exposure when dose and age at first exposure were held constant. Breast cancer incidence was analysed in a cohort of 3090 women diagnosed with benign breast disease during 1925-61 (median age 37 years). Of these, 1216 were treated with radiation therapy. The dose range was 0-50 Gy (mean 5.8 Gy). The incidence rate as function of dose was analysed using a linear-quadratic Poisson regression model. Cell-killing effects and other modifying effects were incorporated through additional log-linear terms. Additive and multiplicative models were compared in estimating the time-related excess. The analysis, which was based on 278 breast cancer cases, showed a linear dose-response relationship at low to medium dose levels with a cell-killing effect of 5% Gy-1 (95% confidence interval 2-9%). For a given absorbed dose and age at first exposure the time-related excess was proportional to the background rates with a suggestion that the excess remains throughout life. PMID:7547222

Radiationdose to the radiologist and other personnel was measured during 102 procedures for percutaneous removal of renal calculi from the upper collecting system. A mobile C-arm image intensifier was used to guide entrance to the kidney and stone removal. Average fluoroscopy time was 25 min. Exposure to personnel was monitored by quartz-fiber dosimeters at the collar level above the lead apron. Average radiationdose to the radiologist was 10 mrem (0.10 mSv) per case; to the surgical nurse, 4 mrem (0.04 mSv) per case; to the radiologic technologist, 4 mrem (0.04 mSv) per case; and to the anesthesiologist, 3 mrem (0.03 mSv) per case. Radiationdose to the uroradiologic team during percutaneous nephrostolithotomy is similar to that from other interventional fluoroscopic procedures and is within acceptable limits for both physicians and assisting personnel.

Topics covered in the review include: current radiation protection standards for workers; current radiation protection standards for the routine exposures of the public; environmental radiation standards for specific practices or sources; protective action guides for accidental releases of radioactivity to the environment; de minimis dose, exempt levels of radioactivity, and below regulatory concern.

Topics covered in the review include: current radiation protection standards for workers; current radiation protection standards for the routine exposures of the public; environmental radiation standards for specific practices or sources; protective action guides for accidental releases of radioactivity to the environment; de minimis dose, exempt levels of radioactivity, and below regulatory concern.

Over many years, Committee 2 of the International Commission on Radiological Protection (ICRP) has provided sets of dose coefficients to allow users to evaluate equivalent and effective doses for intakes of radionuclides or exposure to external radiation for comparison with dose limits, constraints, and reference levels as recommended by ICRP. Following the 2007 Recommendations, Committee 2 and its task groups are engaged in a substantial programme of work to provide new dose coefficients for various conditions of radiation exposure. The methodology being applied in the calculation of doses can be regarded as state-of-the-art in terms of the biokinetic models used to describe the behaviour of inhaled and ingested radionuclides, and the dosimetric models used to model radiation transport for external and internal exposures. The level of sophistication of these models is greater than required for calculation of the protection quantities with their inherent simplifications and approximations, which were introduced necessarily, for example by the use of radiation and tissue weighting factors. However, ICRP is at the forefront of developments in this area, and its models are used for scientific as well as protection purposes. This overview provides an outline of recent work and future plans, including publications on dose coefficients for adults, children, and in-utero exposures, with new dosimetric phantoms in each case. The Committee has also recently finished a report on radiation exposures of astronauts in space, and is working with members of the other ICRP committees on the development of advice on the use of effective dose. PMID:25816256

In the decade after the bombings of Hiroshima and Nagasaki, several large cohorts of survivors were organized for studies of radiation health effects. The U.S. Atomic Bomb Casualty Commission (ABCC) and its U.S./Japan successor, the Radiation Effects Research Foundation (RERF), have performed continuous studies since then, with extensive efforts to collect data on survivor locations and shielding and to create systems to estimate individual doses from the bombs' neutrons and gamma rays. Several successive systems have been developed by extramural working groups and collaboratively implemented by ABCC and RERF investigators. We describe the cohorts and the history and evolution of doseestimation from early efforts through the newest system, DS02, emphasizing the technical development and use of DS02. We describe procedures and data developed at RERF to implement successive systems, including revised rosters of survivors, development of methods to calculate doses for some classes of persons not fitting criteria of the basic systems, and methods to correct for bias arising from errors in calculated doses. We summarize calculated doses and illustrate their change and elaboration through the various systems for a hypothetical example case in each city. We conclude with a description of current efforts and plans for further improvements. PMID:16808610

The flight of a human phantom torso with head that containing active dosimeters at 5 organ sites and 1400 TLDs distributed in 34 1" thick sections is described. Experimental dose rates and quality factors are compared with calculations for shielding distributions at the sites using the Computerized Anatomical Male (CAM) model. The measurements were complemented with those obtained from other instruments. These results have provided the most comprehensive data set to map the dose distribution inside a human and to assess the accuracy of radiation transport models and astronaut radiation risk.

Excess exposure to UV radiation can affect our health by causing sunburn, skin cancer, etc. It is therefore useful to determine the UV dosage received by people as a way of protecting them from the possible negative effects that this kind of radiation can cause. In this work, the personal outdoor percentage, which shows the time spent in outdoor activities, as well as personal UV doses, has been calculated by means of global UV radiation on a horizontal plane. A database of average daily UVB radiation on the horizontal plane given by the National Institute of Meteorology has been used. In this work we evaluate the standard erythema dose of the Spanish population throughout the year. PMID:18028210

In radiation therapy, commercially available medical linear accelerators (LINACs) are used. At high primary beam energies in the 10-MeV range, the leakage dose of the accelerator head and the backscatter from the room walls, the air and the patient become more important. Therefore, radiation protection measurements of photon dose rates in the treatment room and in the maze are performed to quantify the radiation field. Since the radiation of the LINACs is usually pulsed with short radiation pulse durations in the microsecond range, there are problems with electronic dose (rate) meters commonly used in radiation protection. In this paper measurements with ionisation chambers are presented and electronic dosemeters are used for testing at selected positions. The measured time-averaged dose rate ranges from a few microsieverts per hour in the maze to some millisieverts per hour in the vicinity of the accelerator head and up to some sieverts per hour in the blanked primary beam and several hundred sieverts per hour in the direct primary beam. PMID:24379437

Purpose To investigate the impact of radiationdose on breast density estimation in digital mammography. Materials and Methods With institutional review board approval and Health Insurance Portability and Accountability Act compliance under waiver of consent, a cohort of women from the American College of Radiology Imaging Network Pennsylvania 4006 trial was retrospectively analyzed. All patients underwent breast screening with a combination of dose protocols, including standard full-field digital mammography, low-dose digital mammography, and digital breast tomosynthesis. A total of 5832 images from 486 women were analyzed with previously validated, fully automated software for quantitative estimation of density. Clinical Breast Imaging Reporting and Data System (BI-RADS) density assessment results were also available from the trial reports. The influence of image acquisition radiationdose on quantitative breast density estimation was investigated with analysis of variance and linear regression. Pairwise comparisons of density estimations at different dose levels were performed with Student t test. Agreement of estimation was evaluated with quartile-weighted Cohen kappa values and Bland-Altman limits of agreement. Results Radiationdose